app-server: keep the model cache warm

[jif-oai]

Why

The app server is long-lived, but its shared model cache otherwise refreshes only when a caller needs it. Once the five-minute cache expires, starting a thread or calling model/list can wait for /models on the request path.

Refresh the cache in the background before it expires so foreground callers normally use fresh local state.

What changed

• Start an app-server worker that refreshes models immediately and then every three minutes using the existing models-manager API.
• Hold only a weak reference to the models manager between refreshes, so the worker does not extend its lifetime.
• Stop scheduling refreshes when the app-server lifecycle handle is shut down or dropped. A refresh already in progress is allowed to finish.
• Adjust affected app-server test fixtures to distinguish the background /models probe from the connection they are testing.

The existing models-manager cache, refresh strategies, auth handling, ETag behavior, and concurrency semantics are unchanged.

Testing

• models_refresh_worker::tests::refreshes_immediately_periodically_and_stops_when_dropped
• suite::v2::remote_control::listen_off_honors_persisted_remote_control_enable
• suite::v2::attestation::attestation_generate_round_trip_adds_header_to_responses_websocket_handshake

[chatgpt-codex-connector]

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