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/sidecar/Get System Configuration.bru

@@ -1,20 +1,57 @@
 meta {
-  name: "Get System Configuration"
+  name: Get System Configuration
   type: http
   seq: 3
 }
 
 get {
   url: {{base_url}}/api/system/config
-  auth: {
-    type: bearer
-    bearer: {{admin_token}}
-  }
+  body: none
+  auth: inherit
 }
 
-assert {
-  response.status == 200
-  response.body.base_url exists()
-  response.body.opds_base_url exists()
-  response.body.api_base_url exists()
+headers {
+  Authorization: Bearer {{admin_token}}
+  Content-Type: application/json
+}
+
+script:post-response {
+  function onResponse(res) {
+    if (res.getStatus() === 200) {
+      const body = res.getBody();
+      tests('Has base_url', body.base_url !== undefined);
+      tests('Has opds_base_url', body.opds_base_url !== undefined);
+      tests('Has api_base_url', body.api_base_url !== undefined);
+    }
+  }
+  onResponse(res);
+}
+
+settings {
+  encodeUrl: true
+  timeout: 0
+}
+
+docs {
+  ## Get System Configuration
+
+  Retrieves system-wide configuration settings.
+
+  **Method:** GET
+
+  **Endpoint:** /api/system/config
+
+  **Authentication:** Bearer token (admin only)
+
+  **Response:**
+  - `base_url` (string): Base URL
+  - `opds_base_url` (string): OPDS endpoint URL
+  - `api_base_url` (string): API endpoint URL
+  - Additional configuration fields
+
+  **Status Codes:**
+  - 200: Success
+  - 401: Unauthorized
+  - 403: Forbidden (admin only)
+  - 500: Internal server error
 }