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

@@ -1,5 +1,5 @@
 meta {
-  name: Scan Ebooks (Background)
+  name: Scan Media Items (Background)
   type: http
   seq: 1
 }
@@ -22,9 +22,9 @@ body:json {
 }
 
 docs {
-  ## Scan Ebooks (Background)
+  ## Scan Media Items (Background)
   
-  Triggers an asynchronous ebook scanning operation. The scan runs in the background and can be monitored using the job ID.
+  Triggers an asynchronous media items scanning operation. The scan runs in the background and can be monitored using the job ID.
   
   **Method:** POST
   
@@ -34,7 +34,7 @@ docs {
   
   **Request Body:**
   - `folder_paths` (array of strings, required): List of folder paths to scan
-    - Example: `["/path/to/ebooks", "/another/path"]`
+     - Example: `["/path/to/media", "/another/path"]`
   
   **Response:** HTTP 202 (Accepted)
   ```json

bruno/scanner/Start Watch Mode.bru

@@ -19,7 +19,7 @@ body:json {
 docs {
   ## Start Watch Mode
   
-  Starts real-time file system monitoring for a specific library. New ebooks will be detected and processed almost instantly.
+  Starts real-time file system monitoring for a specific library. New media items will be detected and processed almost instantly.
   
   **Method:** POST