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/Start Watch Mode.bru

@@ -0,0 +1,61 @@
+meta {
+  name: Start Watch Mode
+  type: http
+  seq: 5
+}
+
+post {
+  url: {{base_url}}/api/scanner/watch/start
+  body: json
+  auth: inherit
+}
+
+body:json {
+  {
+    "library_id": "{{library_id}}"
+  }
+}
+
+docs {
+  ## Start Watch Mode
+  
+  Starts real-time file system monitoring for a specific library. New ebooks will be detected and processed almost instantly.
+  
+  **Method:** POST
+  
+  **Endpoint:** /api/scanner/watch/start
+  
+  **Authentication:** Required (Bearer token, Admin only)
+  
+  **Request Body:**
+  - `library_id` (string, required): UUID of the library to watch
+    - Example: `"550e8400-e29b-41d4-a716-446655440000"`
+  
+  **Response:** HTTP 200 (OK)
+  ```json
+  {
+    "message": "watch mode started for library",
+    "library_id": "550e8400-e29b-41d4-a716-446655440000"
+  }
+  ```
+  
+  **How it works:**
+  - Monitors all folders configured for the library
+  - Automatically detects new ebook files (CREATE events)
+  - Detects modifications to existing files (WRITE events)
+  - Processes new files within milliseconds of detection
+  - Automatically watches new subdirectories as they're created
+  
+  **Supported file types:**
+  - `.epub`, `.pdf`, `.mobi`, `.azw3`, `.fb2`, `.txt`
+  
+  **Status Codes:**
+  - 200: Watch mode started successfully
+  - 400: Invalid request (missing library_id)
+  - 401: Unauthorized
+  - 403: Forbidden (admin access required)
+  - 409: Already watching this library
+  - 500: Failed to start watch mode (no folders configured, etc.)
+  
+  **Note:** Watch mode is automatically started for all libraries when the server starts.
+}