feat: unified rail shell, robust live sync, task board performance

Shell:
- One shared NexusLayout for ALL routes (dashboard + pages): compact 68px
  icon rail with hover-expand overlay, replaces both old sidebars + topbars
- Single flat nav source (railNav) — same menu everywhere incl. Settings
- Removed dead shell components (AppSidebar, AppHeader, Topbar, NavGroup,
  NavItem, ModuleView) and dead nav routes; App.vue is now just RouterView

Live updates:
- Fix SSE loop in DashboardController: PeriodicTimer.WaitForNextTickAsync and
  ChannelReader.ReadAsync were re-invoked while pending — every published
  update threw InvalidOperationException and killed ALL live streams
- liveSync store: treat graceful stream close as disconnect (was stuck
  connected=true with polling stopped -> page frozen until manual reload),
  fast first retry, heartbeat watchdog (65s), reconnect on online/visibility
- One app-wide SSE connection owned by the layout instead of per-view
  connect/disconnect churn; removed duplicate live-sync.ts store

Performance:
- Board endpoint: drop nested childTasks duplication (counts stay) — payload
  104KB -> 65KB; SSE snapshots shrink equally
- nginx: gzip for JSON/JS/CSS (board 18KB, bundle 95KB over the wire);
  text/event-stream excluded to keep SSE unbuffered

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/stores/live-sync.ts

@@ -1,172 +0,0 @@
-import { defineStore } from 'pinia'
-import { openDashboardLiveStream } from '../services/live'
-import type { BoardGroup, DashboardTaskDto } from './tasks'
-import type { NotificationItem } from './notifications'
-import type { TaskItem } from '../components/dashboard/v2/types'
-import { useTaskStore } from './tasks'
-import { useNotificationStore } from './notifications'
-import type { DashboardLiveEventDto, LiveCursorDto, LiveUpdateEnvelope } from '../services/live'
-
-interface NotificationSnapshotDto {
-  notifications: NotificationItem[]
-  unreadCount: number
-  forUser: string
-}
-
-interface DashboardLiveSnapshotDto {
-  board: BoardGroup
-  notifications: NotificationSnapshotDto
-  cursor: LiveCursorDto
-}
-
-function isBoardGroup(value: unknown): value is BoardGroup {
-  const v = value as BoardGroup
-  return !!v && Array.isArray(v.offen) && Array.isArray(v.inProgress) && Array.isArray(v.review) && Array.isArray(v.blocked) && Array.isArray(v.done)
-}
-
-function mapTasks(board: BoardGroup): DashboardTaskDto[] {
-  return [...board.offen, ...board.inProgress, ...board.review, ...board.blocked, ...board.done]
-}
-
-function mapTaskStripItem(t: DashboardTaskDto): TaskItem {
-  return {
-    id: t.id,
-    title: t.title,
-    agent: t.assignedTo ?? '—',
-    priority: (['high', 'critical', 'urgent'].includes(t.priority.toLowerCase()) ? 'high' : ['low', 'minor'].includes(t.priority.toLowerCase()) ? 'low' : 'medium') as 'high' | 'medium' | 'low',
-    status: (t.state.toLowerCase() === 'blocked' ? 'blocked' : (['in progress', 'active', 'working'].includes(t.state.toLowerCase()) ? 'active' : 'pending')) as 'active' | 'blocked' | 'pending',
-    progress: t.state.toLowerCase() === 'done' ? 100 : t.state.toLowerCase() === 'blocked' ? 30 : (['in progress', 'active', 'working'].includes(t.state.toLowerCase()) ? 50 : 0),
-    detail: t.detail,
-    source: t.source,
-  }
-}
-
-export const useLiveSyncStore = defineStore('liveSync', {
-  state: () => ({
-    connected: false,
-    connecting: false,
-    lastEventAt: null as string | null,
-    lastHeartbeatAt: null as string | null,
-    error: null as string | null,
-    controller: null as AbortController | null,
-    reconnectTimer: null as ReturnType<typeof setTimeout> | null,
-    mode: 'polling' as 'polling' | 'live',
-    lastSequence: 0,
-    reconnectAttempts: 0,
-  }),
-
-  getters: {
-    liveIndicatorLabel: (state) => {
-      if (state.connecting) return 'Verbinde…'
-      if (state.connected) return `Live · #${state.lastSequence}`
-      return state.mode === 'polling' ? 'Polling' : 'Offline'
-    },
-    connectionHealth: (state) => {
-      if (state.connected) return 'healthy'
-      if (state.connecting) return 'connecting'
-      return 'degraded'
-    },
-  },
-
-  actions: {
-    async connect(forUser = 'bao') {
-      if (this.connecting || this.connected) return
-      this.connecting = true
-      this.error = null
-      this.controller = new AbortController()
-
-      const taskStore = useTaskStore()
-      const notificationStore = useNotificationStore()
-
-      try {
-        const stream = await openDashboardLiveStream((event, data) => {
-          this.lastEventAt = new Date().toISOString()
-
-          if (event === 'heartbeat') {
-            const cursor = data as LiveCursorDto
-            this.lastHeartbeatAt = cursor.timestamp
-            this.lastSequence = Math.max(this.lastSequence, cursor.sequence)
-            return
-          }
-
-          if (event === 'snapshot') {
-            const snapshot = data as DashboardLiveSnapshotDto
-            taskStore.board = snapshot.board
-            taskStore.tasks = mapTasks(snapshot.board).map(mapTaskStripItem)
-            notificationStore.notifications = snapshot.notifications.notifications
-            notificationStore.unreadCount = snapshot.notifications.unreadCount
-            this.lastSequence = snapshot.cursor.sequence
-            this.connected = true
-            this.mode = 'live'
-            this.reconnectAttempts = 0
-            taskStore.stopBoardPolling()
-            return
-          }
-
-          const eventDto = data as DashboardLiveEventDto
-          this.applyEnvelope(eventDto.envelope, forUser)
-          this.lastSequence = eventDto.cursor.sequence
-          this.connected = true
-          this.mode = 'live'
-          this.reconnectAttempts = 0
-          taskStore.stopBoardPolling()
-        }, { forUser, signal: this.controller.signal, afterSequence: this.lastSequence || null })
-
-        await stream.closed
-      } catch (error) {
-        if (this.controller?.signal.aborted) return
-        console.warn('[liveSync] stream failed, falling back to polling', error)
-        this.error = 'Live updates unavailable'
-        this.connected = false
-        this.mode = 'polling'
-        taskStore.startBoardPolling()
-        this.scheduleReconnect(forUser)
-      } finally {
-        this.connecting = false
-        if (!this.controller?.signal.aborted && !this.connected) {
-          this.mode = 'polling'
-        }
-      }
-    },
-
-    applyEnvelope(envelope: LiveUpdateEnvelope, forUser: string) {
-      const taskStore = useTaskStore()
-      const notificationStore = useNotificationStore()
-
-      if (envelope.type === 'tasks.board.snapshot' && isBoardGroup(envelope.payload)) {
-        taskStore.board = envelope.payload
-        taskStore.tasks = mapTasks(envelope.payload).map(mapTaskStripItem)
-        return
-      }
-
-      if (envelope.type === 'notifications.snapshot') {
-        const snapshot = envelope.payload as NotificationSnapshotDto
-        if (snapshot.forUser !== forUser) return
-        notificationStore.notifications = snapshot.notifications
-        notificationStore.unreadCount = snapshot.unreadCount
-      }
-    },
-
-    disconnect() {
-      this.controller?.abort()
-      this.controller = null
-      this.connected = false
-      this.connecting = false
-      this.mode = 'polling'
-      if (this.reconnectTimer) {
-        clearTimeout(this.reconnectTimer)
-        this.reconnectTimer = null
-      }
-    },
-
-    scheduleReconnect(forUser = 'bao') {
-      if (this.reconnectTimer) return
-      const delay = Math.min(30000, 5000 * Math.max(1, this.reconnectAttempts + 1))
-      this.reconnectAttempts += 1
-      this.reconnectTimer = setTimeout(() => {
-        this.reconnectTimer = null
-        this.connect(forUser)
-      }, delay)
-    },
-  },
-})

frontend/src/stores/liveSync.ts

@@ -50,9 +50,11 @@ export const useLiveSyncStore = defineStore('liveSync', {
     error: null as string | null,
     controller: null as AbortController | null,
     reconnectTimer: null as ReturnType<typeof setTimeout> | null,
+    watchdogTimer: null as ReturnType<typeof setInterval> | null,
     mode: 'polling' as 'polling' | 'live',
     lastSequence: 0,
     reconnectAttempts: 0,
+    forUser: 'bao',
   }),
 
   getters: {
@@ -73,7 +75,9 @@ export const useLiveSyncStore = defineStore('liveSync', {
       if (this.connecting || this.connected) return
       this.connecting = true
       this.error = null
+      this.forUser = forUser
       this.controller = new AbortController()
+      this.startWatchdog()
 
       const taskStore = useTaskStore()
       const notificationStore = useNotificationStore()
@@ -113,19 +117,51 @@ export const useLiveSyncStore = defineStore('liveSync', {
         }, { forUser, signal: this.controller.signal, afterSequence: this.lastSequence || null })
 
         await stream.closed
+        // Stream „sauber" beendet (Proxy-Timeout, Server-Neustart, Netzwechsel):
+        // muss genauso wie ein Fehler behandelt werden — sonst bleibt connected=true
+        // hängen, Polling ist gestoppt und die Seite erhält nie wieder Updates.
       } catch (error) {
-        if (this.controller?.signal.aborted) return
-        console.warn('[liveSync] stream failed, falling back to polling', error)
-        this.error = 'Live updates unavailable'
-        this.connected = false
-        this.mode = 'polling'
-        taskStore.startBoardPolling()
-        this.scheduleReconnect(forUser)
+        if (!this.controller?.signal.aborted) {
+          console.warn('[liveSync] stream failed', error)
+          this.error = 'Live updates unavailable'
+        }
       } finally {
         this.connecting = false
-        if (!this.controller?.signal.aborted && !this.connected) {
-          this.mode = 'polling'
+      }
+
+      if (this.controller?.signal.aborted) return
+
+      this.connected = false
+      this.mode = 'polling'
+      taskStore.startBoardPolling()
+      this.scheduleReconnect(forUser)
+    },
+
+    /** Erzwingt einen frischen Stream (Watchdog / visibilitychange / online). */
+    reconnectNow() {
+      const forUser = this.forUser
+      this.disconnect()
+      this.connect(forUser)
+    },
+
+    startWatchdog() {
+      if (this.watchdogTimer) return
+      this.watchdogTimer = setInterval(() => {
+        if (!this.connected || !this.lastEventAt) return
+        // Heartbeat kommt alle 20s — >65s Stille heißt: Verbindung ist tot,
+        // auch wenn der Browser den fetch-Stream noch für offen hält.
+        const silentMs = Date.now() - new Date(this.lastEventAt).getTime()
+        if (silentMs > 65000) {
+          console.warn('[liveSync] heartbeat timeout, reconnecting')
+          this.reconnectNow()
         }
+      }, 15000)
+    },
+
+    stopWatchdog() {
+      if (this.watchdogTimer) {
+        clearInterval(this.watchdogTimer)
+        this.watchdogTimer = null
       }
     },
 
@@ -148,6 +184,7 @@ export const useLiveSyncStore = defineStore('liveSync', {
     },
 
     disconnect() {
+      this.stopWatchdog()
       this.controller?.abort()
       this.controller = null
       this.connected = false
@@ -161,7 +198,9 @@ export const useLiveSyncStore = defineStore('liveSync', {
 
     scheduleReconnect(forUser = 'bao') {
       if (this.reconnectTimer) return
-      const delay = Math.min(30000, 5000 * Math.max(1, this.reconnectAttempts + 1))
+      // Erster Retry schnell (1s) — der häufigste Fall ist ein Proxy-/Deploy-Cut,
+      // danach sanft hochstaffeln bis 30s.
+      const delay = this.reconnectAttempts === 0 ? 1000 : Math.min(30000, 5000 * this.reconnectAttempts)
       this.reconnectAttempts += 1
       this.reconnectTimer = setTimeout(() => {
         this.reconnectTimer = null