fix: remove unused imports and variables flagged by CodeQL

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/context.repoMap.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, test, mock, beforeEach } from 'bun:test'
+import { describe, expect, test } from 'bun:test'
 
 // The feature() function from bun:bundle is shimmed at build time.
 // In tests, it's not available, so we test the getRepoMapContext logic