Add envcheck diagnostic (key names only)

node_probe.py

@@ -48,6 +48,11 @@ def register_routes(fa_app):
             "backend_dir": node_runtime.BACKEND_DIR,
         })
 
+    @fa_app.get("/respite/v2/node/envcheck")
+    def _envcheck():
+        keys = sorted(k for k in os.environ if "API" in k.upper() or "KEY" in k.upper() or "TOKEN" in k.upper())
+        return JSONResponse({"matching_keys": keys, "hf_token_present": bool(os.environ.get("HF_TOKEN"))})
+
     @fa_app.get("/respite/v2/node/version")
     def _version():
         node = _node_path()