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/lib/nativeDialog.ts

@@ -1,36 +1,109 @@
-/**
- * Native OS dialog helpers
- * Calls server-side endpoints that open system-native file/folder picker dialogs.
- */
+// ========================================
+// Native OS Dialog Helpers
+// ========================================
+// Calls server-side endpoints that open system-native file/folder picker dialogs.
+// Returns structured DialogResult objects for clear success/cancel/error handling.
 
-export async function selectFolder(initialDir?: string): Promise<string | null> {
+/**
+ * Represents the result of a native dialog operation.
+ */
+export interface DialogResult {
+  /** The selected path. Null if cancelled or an error occurred. */
+  path: string | null;
+  /** True if the user cancelled the dialog. */
+  cancelled: boolean;
+  /** An error message if the operation failed. */
+  error?: string;
+}
+
+/**
+ * Opens a native OS folder selection dialog.
+ * 
+ * @param initialDir - Optional directory to start the dialog in
+ * @returns DialogResult with path, cancelled status, and optional error
+ * 
+ * @example
+ * ```typescript
+ * const result = await selectFolder('/home/user/projects');
+ * if (result.path) {
+ *   console.log('Selected:', result.path);
+ * } else if (result.cancelled) {
+ *   console.log('User cancelled');
+ * } else if (result.error) {
+ *   console.error('Error:', result.error);
+ * }
+ * ```
+ */
+export async function selectFolder(initialDir?: string): Promise<DialogResult> {
   try {
     const res = await fetch('/api/dialog/select-folder', {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({ initialDir }),
     });
-    if (!res.ok) return null;
+
+    if (!res.ok) {
+      return {
+        path: null,
+        cancelled: false,
+        error: `Server responded with status: ${res.status}`,
+      };
+    }
+
     const data = await res.json();
-    if (data.cancelled) return null;
-    return data.path || null;
-  } catch {
-    return null;
+    if (data.cancelled) {
+      return { path: null, cancelled: true };
+    }
+
+    return { path: data.path || null, cancelled: false };
+  } catch (err) {
+    const message = err instanceof Error ? err.message : 'An unknown error occurred';
+    return { path: null, cancelled: false, error: message };
   }
 }
 
-export async function selectFile(initialDir?: string): Promise<string | null> {
+/**
+ * Opens a native OS file selection dialog.
+ * 
+ * @param initialDir - Optional directory to start the dialog in
+ * @returns DialogResult with path, cancelled status, and optional error
+ * 
+ * @example
+ * ```typescript
+ * const result = await selectFile('/home/user/documents');
+ * if (result.path) {
+ *   console.log('Selected:', result.path);
+ * } else if (result.cancelled) {
+ *   console.log('User cancelled');
+ * } else if (result.error) {
+ *   console.error('Error:', result.error);
+ * }
+ * ```
+ */
+export async function selectFile(initialDir?: string): Promise<DialogResult> {
   try {
     const res = await fetch('/api/dialog/select-file', {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({ initialDir }),
     });
-    if (!res.ok) return null;
+
+    if (!res.ok) {
+      return {
+        path: null,
+        cancelled: false,
+        error: `Server responded with status: ${res.status}`,
+      };
+    }
+
     const data = await res.json();
-    if (data.cancelled) return null;
-    return data.path || null;
-  } catch {
-    return null;
+    if (data.cancelled) {
+      return { path: null, cancelled: true };
+    }
+
+    return { path: data.path || null, cancelled: false };
+  } catch (err) {
+    const message = err instanceof Error ? err.message : 'An unknown error occurred';
+    return { path: null, cancelled: false, error: message };
   }
 }