feat: consolidate test mocks with centralized index

- Add mock aggregator for cleaner test imports
- Export fetch and uuid mocks from single entry point
- Reduce mock import complexity in test files
- Improve test maintainability and organization

tests/__mocks__/index.js

@@ -0,0 +1,5 @@
+// Consolidated mock exports
+module.exports = {
+  fetch: require('./node-fetch'),
+  uuid: require('./uuid'),
+};