feat: add websocket auth for app-server

[viyatb-oai]

Summary

This change adds websocket authentication at the app-server transport boundary and enforces it before JSON-RPC initialize, so authenticated deployments reject unauthenticated clients during the websocket handshake rather than after a connection has already been admitted.

During rollout, websocket auth is opt-in for non-loopback listeners so we do not break existing remote clients. If --ws-auth ... is configured, the server enforces auth during websocket upgrade. If auth is not configured, non-loopback listeners still start, but app-server logs a warning and the startup banner calls out that auth should be configured before real remote use.

The server supports two auth modes: a file-backed capability token, and a standard HMAC-signed JWT/JWS bearer token verified with the jsonwebtoken crate, with optional issuer, audience, and clock-skew validation. Capability tokens are normalized, hashed, and compared in constant time. Short shared secrets for signed bearer tokens are rejected at startup. Requests carrying an Origin header are rejected with 403 by transport middleware, and authenticated clients present credentials as Authorization: Bearer <token> during websocket upgrade.

Validation

• cargo test -p codex-app-server transport::auth
• cargo test -p codex-cli app_server_
• cargo clippy -p codex-app-server --all-targets -- -D warnings
• just bazel-lock-check

Note: in the broad cargo test -p codex-app-server connection_handling_websocket run, the touched websocket auth cases passed, but unrelated Unix shutdown tests failed with a timeout in this environment.

[etraut-openai]

@codex review

[chatgpt-codex-connector]

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[etraut-openai]

@codex security review

[chatgpt-codex-connector]

Security review completed. No security issues were found in this pull request.

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[etraut-openai]

The implementation looks good to me.

I have some concerns about this from a usability standpoint. The "signed bearer token" auth method is very advanced and will not be appropriate for most codex users and use cases. The capability token approach is easier to configure, but it still requires multiple steps. We'll need to document this very well to help users get through the steps.