feat: add DDD scan, sync, and update commands for document indexing

- Implemented `/ddd:scan` command to analyze existing codebases and generate document indices without specifications. This includes phases for project structure analysis, component discovery, feature inference, and requirement extraction.
- Introduced `/ddd:sync` command for post-task synchronization, updating document indices, generating action logs, and refreshing feature/component documentation after development tasks.
- Added `/ddd:update` command for lightweight incremental updates to the document index, allowing for quick impact checks during development and pre-commit validation.
- Created `execute.md` for the coordinator role in the team lifecycle, detailing the spawning of executor team-workers for IMPL tasks.
- Added `useHasHydrated` hook to determine if the Zustand workflow store has been rehydrated from localStorage, improving state management reliability.

ccw/frontend/src/hooks/useHasHydrated.ts

@@ -0,0 +1,55 @@
+// ========================================
+// useHasHydrated Hook
+// ========================================
+// Determines if the Zustand workflow store has been rehydrated from localStorage
+// Uses Zustand persist middleware's onFinishHydration callback for reliable detection
+
+import { useState, useEffect } from 'react';
+import { useWorkflowStore } from '@/stores/workflowStore';
+
+/**
+ * A hook to determine if the Zustand workflow store has been rehydrated.
+ * Returns `true` once the persisted state has been loaded from localStorage.
+ * 
+ * This hook uses the Zustand persist middleware's onFinishHydration callback
+ * instead of relying on internal state management, which avoids circular
+ * reference issues during store initialization.
+ * 
+ * @example
+ * ```tsx
+ * function MyComponent() {
+ *   const hasHydrated = useHasHydrated();
+ *   
+ *   useEffect(() => {
+ *     if (!hasHydrated) return;
+ *     // Safe to access persisted store values here
+ *   }, [hasHydrated]);
+ *   
+ *   if (!hasHydrated) return <LoadingSpinner />;
+ *   return <Content />;
+ * }
+ * ```
+ */
+export function useHasHydrated(): boolean {
+  const [hydrated, setHydrated] = useState(() => {
+    // Check initial hydration status synchronously
+    return useWorkflowStore.persist.hasHydrated();
+  });
+
+  useEffect(() => {
+    // If already hydrated, no need to subscribe
+    if (hydrated) return;
+
+    // Subscribe to hydration completion event
+    // onFinishHydration returns an unsubscribe function
+    const unsubscribe = useWorkflowStore.persist.onFinishHydration(() => {
+      setHydrated(true);
+    });
+
+    return unsubscribe;
+  }, [hydrated]);
+
+  return hydrated;
+}
+
+export default useHasHydrated;