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/tsconfig.json

@@ -1,6 +1,7 @@
 {
   "extends": "@macalinao/tsconfig/tsconfig.base.json",
   "compilerOptions": {
-    "isolatedDeclarations": false
+    "isolatedDeclarations": false,
+    "types": ["bun"]
   }
 }