feat(M13 PBI-31 T-519b/T-520b): NavBar stand-by badge + quota-check runbook (#119)

* feat(M13 T-519b): SSE worker_heartbeat + NavBar stand-by badge

Aanvulling op scrum4me-mcp PR #25 (worker_heartbeat MCP-tool).

- app/api/realtime/solo/route.ts: WorkerHeartbeatPayload type +
  isWorkerHeartbeatPayload guard + shouldEmit-routing op user_id.
- stores/solo-store.ts: workerQuotaPct + workerQuotaCheckAt state +
  setWorkerQuota action. Reset bij decrementWorkers naar 0.
- lib/realtime/use-solo-realtime.ts: handle worker_heartbeat-event,
  roep setWorkerQuota.
- components/solo/nav-status-indicators.tsx: stand-by badge wanneer
  workerQuotaPct < minQuotaPct + tooltip met drempel.
- components/shared/nav-bar.tsx + app/(app)/layout.tsx: minQuotaPct
  prop plumbing van User.min_quota_pct naar NavStatusIndicators.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* docs(M13 T-520b): pre-flight quota-check sectie in mcp-integration

Documenteert de batch-loop-uitbreiding:
1. get_worker_settings → min_quota_pct
2. bin/worker-quota-probe.sh → pct + reset
3. worker_heartbeat naar server (NavBar stand-by-badge)
4. Sleep tot reset bij low quota; anders wait_for_job

Verwijst naar bin/worker-quota-probe.sh in scrum4me-docker (zie
PR daar).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

components/shared/nav-bar.tsx

@@ -30,6 +30,7 @@ interface NavBarProps {
   activeProduct: { id: string; name: string } | null
   products: { id: string; name: string }[]
   hasActiveSprint: boolean
+  minQuotaPct: number
 }
 
 export function NavBar({
@@ -41,6 +42,7 @@ export function NavBar({
   activeProduct,
   products,
   hasActiveSprint,
+  minQuotaPct,
 }: NavBarProps) {
   const pathname = usePathname()
   const router = useRouter()
@@ -188,7 +190,7 @@ export function NavBar({
 
       {/* Rechts: solo-status + notifications + account-menu */}
       <div className="flex items-center gap-2 flex-1 justify-end">
-        <SoloNavStatusIndicators hasActiveProduct={!!activeProduct} />
+        <SoloNavStatusIndicators hasActiveProduct={!!activeProduct} minQuotaPct={minQuotaPct} />
         <NotificationsBell currentUserId={userId} isDemo={isDemo} />
         <UserMenu userId={userId} username={username} email={email} roles={roles} />
       </div>