feat(ST-qfpqpxzy): SSE + NavBar stand-by badge voor worker quota-gate

- SSE route: WorkerHeartbeatPayload type + shouldEmit handler voor worker_heartbeat
- solo-store: lowQuotaTokenIds Set<string> + setWorkerLowQuota action
- use-solo-realtime: worker_heartbeat event → setWorkerLowQuota; worker_disconnected verwijdert uit set
- nav-status-indicators: stand-by badge (bg-warning) als alle workers low quota
- docs/runbooks/mcp-integration.md: get_worker_settings + worker_heartbeat tools + pre-flight quota-check sectie

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

stores/solo-store.ts

@@ -63,6 +63,7 @@ interface SoloStore {
 
   claudeJobsByTaskId: Record<string, JobState>
   connectedWorkers: number
+  lowQuotaTokenIds: Set<string>
 
   initTasks: (tasks: SoloTask[]) => void
   optimisticMove: (taskId: string, toStatus: TaskStatus) => TaskStatus | null
@@ -82,6 +83,7 @@ interface SoloStore {
   setWorkers: (count: number) => void
   incrementWorkers: () => void
   decrementWorkers: () => void
+  setWorkerLowQuota: (tokenId: string, isLow: boolean) => void
 
   handleRealtimeEvent: (event: RealtimeEvent) => void
 }
@@ -93,6 +95,7 @@ export const useSoloStore = create<SoloStore>((set, get) => ({
   showConnectingIndicator: false,
   claudeJobsByTaskId: {},
   connectedWorkers: 0,
+  lowQuotaTokenIds: new Set<string>(),
 
   initTasks: (tasks) =>
     set({ tasks: Object.fromEntries(tasks.map(t => [t.id, t])) }),
@@ -146,6 +149,13 @@ export const useSoloStore = create<SoloStore>((set, get) => ({
   setWorkers: (count) => set({ connectedWorkers: Math.max(0, count) }),
   incrementWorkers: () => set(s => ({ connectedWorkers: s.connectedWorkers + 1 })),
   decrementWorkers: () => set(s => ({ connectedWorkers: Math.max(0, s.connectedWorkers - 1) })),
+  setWorkerLowQuota: (tokenId, isLow) =>
+    set(s => {
+      const next = new Set(s.lowQuotaTokenIds)
+      if (isLow) next.add(tokenId)
+      else next.delete(tokenId)
+      return { lowQuotaTokenIds: next }
+    }),
 
   handleJobEvent: (event) => {
     const { job_id, task_id } = event