test: add Bruno API collections for sync features

- Add device registration and management API tests
- Add conflicts resolution API tests
- Add queue management API tests
- Add KOReader sync protocol tests
- Add Kobo sync protocol tests

bruno/queue/Get Device Queue Stats.bru

@@ -0,0 +1,49 @@
+meta {
+  name: Get Device Queue Stats
+  type: http
+  seq: 2
+}
+
+get {
+  url: {{base_url}}/api/queue/devices/{{device_id}}/stats
+  body: none
+  auth: bearer
+}
+
+headers: {
+  Authorization: Bearer {{token}}
+}
+
+docs {
+  ## Get Device Queue Stats
+  
+  Retrieves statistics for a specific device's sync queue.
+  
+  **Method:** GET
+  
+  **Endpoint:** /api/queue/devices/:device_id/stats
+  
+  **Authentication:** Bearer token
+  
+  **Path Parameters:**
+   - `device_id` (string): Device UUID
+  
+  **Response:**
+   - Queue statistics including pending, completed, and failed counts
+  
+  **Status Codes:**
+   - 200: Success
+   - 401: Unauthorized
+   - 404: Device not found
+  
+  **Example Response:**
+   ```json
+   {
+     "device_id": "uuid",
+     "total_items": 10,
+     "pending": 3,
+     "completed": 5,
+     "failed": 2
+   }
+   ```
+}