Add TypeScript to dev dependencies

Author: sorenbs

bun.lock

@@ -73,6 +73,7 @@
     "@durable-streams/server-conformance-tests": "^0.2.1",
     "bun-types": "^1.3.6",
     "fast-check": "^3.14.0",
+    "typescript": "^5.9.2",
     "vitest": "^4.0.18"
   },
   "dependencies": {