Drop gradio-client>=2 pin (gradio 5.7.1 bundles 1.5.0); pin websockets 12.x for sync client

Use WebSocket protocol (matches openenv) — all action buttons should work now

Bump gradio 4.44->5.7.1 (HfFolder removed in huggingface_hub 1.x; gradio 4.x is incompat)

Strip openenv-core dep, use plain httpx (resolves websockets conflict)

Bump Gradio 4.44->5.7.1 (resolves websockets<13 vs openenv-core>=15 conflict)

Initial deploy: play-as-on-call-engineer Gradio demo