chore(deploy): add production caddy setup

src/gapido_demo/app.py

@@ -97,6 +97,11 @@ async def index() -> FileResponse:
     return FileResponse(STATIC_DIR / "index.html")
 
 
+@app.get("/healthz")
+async def healthz() -> dict[str, str]:
+    return {"status": "ok"}
+
+
 @app.post("/api/auth/request-otp")
 async def request_otp(
     body: RequestOtpBody,