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/collections/Test Collection Rules - Empty Rules Array.bru

@@ -0,0 +1,48 @@
+meta {
+  name: Test Collection Rules - Empty Rules Array
+  type: http
+  seq: 5
+}
+
+post {
+  url: {{baseUrl}}/api/collections/test-rules
+  body: json
+  auth: inherit
+}
+
+headers {
+  Content-Type: application/json
+  Authorization: Bearer {{authToken}}
+}
+
+body:json {
+  {
+    "rules": []
+  }
+}
+
+script:post-response {
+  function onResponse(res) {
+    tests['Empty rules rejected'] = res.getStatus() === 400;
+  }
+  onResponse(res);
+}
+
+settings {
+  encodeUrl: true
+  timeout: 0
+}
+
+docs {
+  ## Test Collection Rules - Empty Rules Array
+
+  Tests validation behavior when providing an empty rules array.
+
+  **Expected Result:** 400 Bad Request
+
+  **Validation Rule:** rules array must contain at least one rule object.
+
+  **Purpose:** Ensures the API properly validates input and rejects empty rule sets, preventing accidental queries that would return all books or cause performance issues.
+
+  **Use Case:** Client-side validation should prevent sending empty rules, but the API should also validate to catch malformed requests.
+}