feat: board-first orchestration with Gateway Bridge, live-update, and flow-board

- GatewayBridgeController: MCP-artiger Kommando-Adapter für Agent-zu-Backend
- TaskBridgeService + LiveUpdateService: SSE Live-Sync + Bridge-Kommandos
- FlowBoard.vue: Board-first orchestration dashboard panel
- live-sync.ts store + live.ts service: SSE-basierte Live-Updates
- Nullability-Warnung in HealthController.cs gefixt
- nginx.conf: SSE-Proxy + CORS für Bridge-Endpunkte
- .gitignore: pnpm/corepack local caches ausgeschlossen
- docs: architecture-board-first-orchestration.md hinzugefügt
- README: Backend Bridge API dokumentiert

backend/Services/NotificationService.cs

@@ -4,7 +4,7 @@ using Nexus.Api.Models;
 
 namespace Nexus.Api.Services;
 
-public sealed class NotificationService(NexusDbContext db) : INotificationService
+public sealed class NotificationService(NexusDbContext db, ILiveUpdateService liveUpdateService) : INotificationService
 {
     public async Task<Notification> CreateAsync(string type, string title, string? message, string forUser, Guid? taskId = null, CancellationToken ct = default)
     {
@@ -18,6 +18,7 @@ public sealed class NotificationService(NexusDbContext db) : INotificationServic
         };
         db.Notifications.Add(notification);
         await db.SaveChangesAsync(ct);
+        await PublishSnapshotAsync(notification.ForUser, ct);
         return notification;
     }
 
@@ -42,14 +43,17 @@ public sealed class NotificationService(NexusDbContext db) : INotificationServic
 
         notification.IsRead = true;
         await db.SaveChangesAsync(ct);
+        await PublishSnapshotAsync(notification.ForUser, ct);
         return true;
     }
 
     public async Task<int> MarkAllAsReadAsync(string forUser, CancellationToken ct = default)
     {
+        var normalizedUser = forUser.ToLowerInvariant();
         var count = await db.Notifications
-            .Where(n => n.ForUser == forUser.ToLowerInvariant() && !n.IsRead)
+            .Where(n => n.ForUser == normalizedUser && !n.IsRead)
             .ExecuteUpdateAsync(s => s.SetProperty(n => n.IsRead, true), ct);
+        await PublishSnapshotAsync(normalizedUser, ct);
         return count;
     }
 
@@ -58,4 +62,25 @@ public sealed class NotificationService(NexusDbContext db) : INotificationServic
         return await db.Notifications
             .CountAsync(n => n.ForUser == forUser.ToLowerInvariant() && !n.IsRead, ct);
     }
+
+    public async Task<NotificationSnapshotDto> GetSnapshotAsync(string forUser, int limit = 50, bool unreadOnly = false, CancellationToken ct = default)
+    {
+        var normalizedUser = forUser.ToLowerInvariant();
+        var notifications = await GetForUserAsync(normalizedUser, limit, unreadOnly, ct);
+        var unreadCount = await GetUnreadCountAsync(normalizedUser, ct);
+        return new NotificationSnapshotDto(
+            notifications.Select(MapToDto).ToList(),
+            unreadCount,
+            normalizedUser);
+    }
+
+    private async Task PublishSnapshotAsync(string forUser, CancellationToken ct)
+    {
+        var snapshot = await GetSnapshotAsync(forUser, ct: ct);
+        liveUpdateService.Publish("notifications.snapshot", snapshot, "notifications");
+    }
+
+    private static NotificationDto MapToDto(Notification n) => new(
+        n.Id, n.Type, n.Title, n.Message,
+        n.ForUser, n.TaskId, n.IsRead, n.CreatedAt);
 }