feat: Add admin ebook CRUD operations to Bruno collection

- Add POST /api/ebooks for creating new ebook entries
- Add PUT /api/ebooks/:id for updating existing ebook metadata
- Add DELETE /api/ebooks/:id for deleting ebooks from database
- Include complete request/response examples with all metadata fields
- Support file path, metadata, and publication information updates

bruno/ebooks/Delete Ebook.bru

@@ -0,0 +1,53 @@
+meta {
+  name: Delete Ebook
+  type: http
+  seq: 10
+}
+
+delete {
+  url: {{base_url}}/api/ebooks/{{ebook_id}}
+  body: none
+  auth: inherit
+}
+
+settings {
+  encodeUrl: true
+  timeout: 0
+}
+
+docs {
+  ## Delete Ebook
+  
+  Deletes an ebook from the database.
+  
+  **Method:** DELETE
+  
+  **Endpoint:** /api/ebooks/:id
+  
+  **Authentication:** Required (Admin only)
+  
+  **Path Parameters:**
+  - `id` (string): Ebook ID (UUID)
+  
+  **Response:** No content (204) or success message
+  
+  **Status Codes:**
+  - 204: Ebook deleted successfully (no content)
+  - 400: Bad request (invalid ID format)
+  - 401: Unauthorized
+  - 403: Forbidden (admin access required)
+  - 404: Ebook not found
+  - 500: Internal server error
+  
+  **Features:**
+  - Admin-only endpoint for deleting ebooks
+  - Permanent deletion (cannot be undone)
+  - Cascades to delete related data (reading progress, ratings)
+  - Requires valid UUID format for ebook ID
+  
+  **Important Notes:**
+  - This is a destructive operation
+  - All user reading progress for this ebook will be lost
+  - All user ratings for this ebook will be lost
+  - Use with caution
+}