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

README.md

@@ -3,6 +3,10 @@
 Nexus is the operations platform for the Noveria ecosystem. OpenClaw is an
 adapter-backed agent runtime, not a dependency of the frontend or domain model.
 
+> 📋 **Architektur-Review** (2026-06-22): Board-first Orchestrierung, sichere
+> Backend-Brücke und Gateway-Integration geprüft. Siehe
+> [`docs/architecture-board-first-orchestration.md`](docs/architecture-board-first-orchestration.md)
+
 > CI runs automatically on every push. CD can run **automatically after successful CI**
 > on main (patch-bump default) or can be triggered **manually** (workflow_dispatch) with
 > full parameter control. Main deploys bump/tag a release; arbitrary `git_ref` deploys
@@ -170,6 +174,38 @@ Legacy ModuleView routes (not standalone, rendered through `ModuleView.vue`):
 
 ## API endpoints
 
+### Backend Bridge (Agent-zu-Backend, NICHT Frontend)
+
+Der `/api/bridge/` Pfad ist ein strukturierter MCP-artiger Kommando-Adapter für die
+Agent-zu-Backend-Kommunikation. Kein Frontend-Code ruft diese Endpunkte auf.
+
+Auth: `X-Agent-Id` Header, `X-Nexus-Api-Key`, oder JWT. Rate-Limited (30/min).
+
+| Methode | Pfad | Kommando | Beschreibung |
+|---|---|---|---|
+| `GET` | `/api/bridge/health` | — | Bridge-Health-Check |
+| `POST` | `/api/bridge/tasks` | `create_task` | Neue Top-Level-Task erstellen |
+| `POST` | `/api/bridge/tasks/{id}/children` | `create_child_task` | Child-Task unter Parent erstellen |
+| `PATCH` | `/api/bridge/tasks/{id}/status` | `update_status` | Task-Status ändern |
+| `POST` | `/api/bridge/tasks/{id}/activity` | `append_activity` | Aktivitätseintrag anhängen |
+| `POST` | `/api/bridge/tasks/{id}/handoff` | `handoff` | Task an anderen Agent übergeben |
+| `GET` | `/api/bridge/board` | `get_board` | Vollständiges Task-Board |
+| `GET` | `/api/bridge/tasks/{id}` | `get_task` | Einzelne Task abrufen |
+| `GET` | `/api/bridge/tasks/{id}/children` | `get_children` | Child-Tasks abrufen |
+| `GET` | `/api/bridge/tasks/{id}/activity` | `get_activity` | Task-Aktivität abrufen |
+| `GET` | `/api/bridge/agent-overview` | `get_agent_overview` | Agent-Workflow-Übersicht |
+
+Response-Format (TaskBridgeCommandResponse<T>):
+```json
+{
+  "ok": true,
+  "command": "create_task",
+  "data": { ... },
+  "error": null,
+  "timestamp": "2026-06-22T15:30:00.000Z"
+}
+```
+
 ### Health & Auth (public or rate-limited)
 
 | Method | Path | Auth | Description |