Add @types/bun to api-contract for test file compilation

The test file imports from bun:test which requires bun types. Added
@types/bun dependency and configured tsconfig to include bun types.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/api-contract/package.json

@@ -25,6 +25,7 @@
   "devDependencies": {
     "@macalinao/eslint-config": "catalog:",
     "@macalinao/tsconfig": "catalog:",
+    "@types/bun": "^1.3.5",
     "eslint": "catalog:",
     "typescript": "catalog:"
   }