feat(desktop): add monitor scheduler, Playwright CDP layer, and account health

Move monitor-task scheduling authority onto the client with a durable
file-backed queue that survives restart, drops stale cross-day tasks,
enforces per-platform serialism, and adapts global concurrency from
Electron process metrics. Publish tasks keep their existing FIFO.

Add a hidden Playwright CDP manager that attaches to Electron Chromium
on account session partitions, lets adapters opt into `executionMode:
"playwright"`, and leaves the existing hidden WebContentsView path in
place for current adapters.

Introduce an account-health subsystem with silent probes, projected
health/auth states, and IPC invalidation events so the renderer can
show accurate auth/probe status and verification timestamps.

Server-side, derive and forward title/business_date/scheduler_group_key/
question_text metadata on desktop task events so the local scheduler
can defer same-question fan-out before leasing.

apps/desktop-client/src/renderer/composables/useDesktopRuntime.ts

@@ -11,6 +11,7 @@ const error = shallowRef<string | null>(null);
 let intervalHandle: ReturnType<typeof setInterval> | null = null;
 let subscribers = 0;
 let visibilityListenerBound = false;
+let runtimeInvalidationUnsubscribe: (() => void) | null = null;
 
 function isPageVisible(): boolean {
   return typeof document === "undefined" || document.visibilityState === "visible";
@@ -95,6 +96,18 @@ function bindVisibilityListener() {
   visibilityListenerBound = true;
 }
 
+function bindRuntimeInvalidationListener() {
+  if (runtimeInvalidationUnsubscribe || !window.desktopBridge?.app?.onRuntimeInvalidated) {
+    return;
+  }
+
+  runtimeInvalidationUnsubscribe = window.desktopBridge.app.onRuntimeInvalidated(() => {
+    if (isPageVisible()) {
+      void refreshRuntimeSnapshot();
+    }
+  });
+}
+
 function unbindVisibilityListener() {
   if (!visibilityListenerBound || typeof document === "undefined") {
     return;
@@ -104,10 +117,16 @@ function unbindVisibilityListener() {
   visibilityListenerBound = false;
 }
 
+function unbindRuntimeInvalidationListener() {
+  runtimeInvalidationUnsubscribe?.();
+  runtimeInvalidationUnsubscribe = null;
+}
+
 export function useDesktopRuntime() {
   onMounted(() => {
     subscribers += 1;
     bindVisibilityListener();
+    bindRuntimeInvalidationListener();
     if (!snapshot.value && !loading.value) {
       void refreshRuntimeSnapshot();
     }
@@ -119,6 +138,7 @@ export function useDesktopRuntime() {
     if (subscribers === 0) {
       stopPolling();
       unbindVisibilityListener();
+      unbindRuntimeInvalidationListener();
       return;
     }