fix: remove agent postinstall that breaks frontend build on Render

The postinstall "uv sync" hook runs during pnpm install on the frontend
Node service where uv is not available. The agent service has its own
buildCommand in render.yaml. Also updates dev script to match the new
native FastAPI setup and drops the unused langgraph-cli dependency.

Author: GeneralJerel

apps/agent/package.json

@@ -3,10 +3,6 @@
   "version": "0.1.0",
   "private": true,
   "scripts": {
-    "dev": "npx @langchain/langgraph-cli dev --port 8123 --no-browser",
-    "postinstall": "uv sync"
-  },
-  "devDependencies": {
-    "@langchain/langgraph-cli": "^1.1.12"
+    "dev": "uv run uvicorn main:app --host 0.0.0.0 --port 8123 --reload"
   }
 }