refactor: update Bruno API collection for media-items system

- Remove all ebook-specific API requests (15 files deleted)
- Rename Scan Ebooks.bru to Scan Media Items.bru
- Update API paths from /api/ebooks to /api/media-items
- Update base URL and environment configuration
- Maintain all existing media-items, library, auth, and progress tests

Aligns Bruno collection with unified media-items API architecture

bruno/scanner/Scan Media Items.bru

@@ -0,0 +1,62 @@
+meta {
+  name: Scan Media Items (Background)
+  type: http
+  seq: 1
+}
+
+post {
+  url: {{base_url}}/api/scanner/scan
+  body: json
+  auth: inherit
+}
+
+settings {
+  encodeUrl: true
+  timeout: 0
+}
+
+body:json {
+  {
+    "folder_paths": ["/path/to/ebooks"]
+  }
+}
+
+docs {
+  ## Scan Media Items (Background)
+  
+  Triggers an asynchronous media items scanning operation. The scan runs in the background and can be monitored using the job ID.
+  
+  **Method:** POST
+  
+  **Endpoint:** /api/scanner/scan
+  
+  **Authentication:** Required (Bearer token, Admin only)
+  
+  **Request Body:**
+  - `folder_paths` (array of strings, required): List of folder paths to scan
+     - Example: `["/path/to/media", "/another/path"]`
+  
+  **Response:** HTTP 202 (Accepted)
+  ```json
+  {
+    "message": "scan job enqueued",
+    "job_id": "550e8400-e29b-41d4-a716-446655440000",
+    "status": "pending"
+  }
+  ```
+  
+  **Properties:**
+  - `message` (string): Confirmation message
+  - `job_id` (string): Unique job identifier for tracking progress
+  - `status` (string): Initial job status ("pending")
+  
+  **Status Codes:**
+  - 202: Scan job successfully enqueued
+  - 400: Invalid request (missing folder_paths)
+  - 401: Unauthorized
+  - 403: Forbidden (admin access required)
+  - 500: Failed to enqueue scan job
+  
+  **Next Steps:**
+  Use the returned `job_id` with `GET /api/scanner/status/:jobId` to check scan progress.
+}