docs(scanner): update Bruno requests for new scanner endpoints

- Update Scan Ebooks.bru to reflect async background scanning
- Add Get Scan Status.bru for checking job progress
- Add Start Watch Mode.bru for instant file monitoring
- Add Stop Watch Mode.bru for stopping library monitoring
- Add Get Watch Mode Status.bru for checking watched libraries
- Document all new endpoints with examples and status codes

bruno/scanner/Stop Watch Mode.bru

@@ -0,0 +1,51 @@
+meta {
+  name: Stop Watch Mode
+  type: http
+  seq: 6
+}
+
+post {
+  url: {{base_url}}/api/scanner/watch/stop
+  body: json
+  auth: inherit
+}
+
+body:json {
+  {
+    "library_id": "{{library_id}}"
+  }
+}
+
+docs {
+  ## Stop Watch Mode
+  
+  Stops real-time file system monitoring for a specific library.
+  
+  **Method:** POST
+  
+  **Endpoint:** /api/scanner/watch/stop
+  
+  **Authentication:** Required (Bearer token, Admin only)
+  
+  **Request Body:**
+  - `library_id` (string, required): UUID of the library to stop watching
+    - Example: `"550e8400-e29b-41d4-a716-446655440000"`
+  
+  **Response:** HTTP 200 (OK)
+  ```json
+  {
+    "message": "watch mode stopped for library",
+    "library_id": "550e8400-e29b-41d4-a716-446655440000"
+  }
+  ```
+  
+  **Status Codes:**
+  - 200: Watch mode stopped successfully
+  - 400: Invalid request (missing library_id)
+  - 401: Unauthorized
+  - 403: Forbidden (admin access required)
+  - 404: Not watching this library
+  - 500: Internal server error
+  
+  **Note:** If no libraries are being watched, the watch mode context is cleaned up automatically.
+}