feat: allow editing manager field in cleaner table

- Add inline editing for manager column (Admin users can double-click to select from dropdown)
- Auto-assign current user as manager when User checks a material
- Defer database writes until 'Confirm Delete' button is clicked
- Add updateManager IPC handler and DAO method
- Update preload API with updateManager method

src/preload/index.d.ts

@@ -150,6 +150,15 @@ export interface MaterialsAPI {
    * Get statistics
    */
   getStatistics: () => Promise<{ stats: unknown }>
+  /**
+   * Update manager for a single material
+   * @param materialCode - Material code
+   * @param managerName - New manager name
+   */
+  updateManager: (
+    materialCode: string,
+    managerName: string
+  ) => Promise<{ success: boolean; error?: string }>
 }
 
 /**