refactor(bruno): migrate API tests to Bruno DSL format

- Convert all existing .bru files from JSON to Bruno DSL format
- Remove obsolete files (conflicts/api.bru, kobo/Kobo Initialization.bru)
- Update auth configuration to use 'inherit' instead of explicit bearer tokens
- Add comprehensive documentation to all test files
- Improve test scripts with proper assertions and error handling

bruno/koreader/Get Book Metadata.bru

@@ -6,15 +6,56 @@ meta {
 
 get {
   url: {{baseUrl}}/api/sync/koreader/metadata/{{book_uuid}}
-  headers: {
-    Authorization: Bearer {{device_token}},
-    Content-Type: application/json
-  }
+  body: none
+  auth: inherit
 }
 
-assert {
-  res.status == 200
-  res.body.uuid != null
-  res.body.title != null
-  res.body.progress != null
+headers {
+  Authorization: Bearer {{device_token}}
+  Content-Type: application/json
+}
+
+script:post-response {
+  function onResponse(res) {
+    if (res.getStatus() === 200) {
+      const body = res.getBody();
+      tests['Status is 200'] = true;
+      tests['Has UUID'] = body.uuid !== null;
+      tests['Has title'] = body.title !== null;
+      tests['Has progress'] = body.progress !== null;
+    }
+  }
+  onResponse(res);
+}
+
+settings {
+  encodeUrl: true
+  timeout: 0
+}
+
+docs {
+  ## KOReader Get Book Metadata
+
+  Retrieves metadata for a specific book from the KOReader sync endpoint.
+
+  **Method:** GET
+
+  **Endpoint:** /api/sync/koreader/metadata/{book_uuid}
+
+  **Authentication:** Bearer token (device token)
+
+  **Path Parameters:**
+  - `book_uuid` (string): Book UUID
+
+  **Response:**
+  - `uuid` (string): Book UUID
+  - `title` (string): Book title
+  - `progress` (object): Reading progress data
+  - `metadata` (object): Additional book metadata
+
+  **Status Codes:**
+  - 200: Success
+  - 401: Unauthorized
+  - 404: Book not found
+  - 500: Internal server error
 }