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/user/admin/Delete Account.bru

@@ -49,5 +49,5 @@ docs {
   - Cannot delete the last admin account in the system
   - Admin role required to use user_id parameter
   
-  **Warning:** This action cannot be undone and will permanently delete all user data including ebooks, ratings, and progress.
+   **Warning:** This action cannot be undone and will permanently delete all user data including media items, ratings, and progress.
 }

bruno/user/auth/Register User.bru

@@ -23,11 +23,11 @@ body:json {
 script:post-response {
   function onResponse(res) {
     let data = res.getBody();
-  
     // If successful registration, set token environment variable
     if (res.getStatus() === 201 || res.getStatus() === 200) {
-      if (data && data.token) {
-        return bru.setEnvVar("token", data.token, { persist: true });
+      if (data && data.access_token) {
+  
+        return bru.setEnvVar("token", data.access_token, { persist: true });
       }
     }
   }