fix(voice): defer OpenAI Keychain access

[johnmatthewtennant]

Summary

• Read the shared OpenAI voice credential only when the selected Voice settings need it, while keeping OpenAI TTS selectable before that read.
• Coalesce concurrent mount-time status requests and force fresh status reads after credential changes.
• Use only Berd’s shared berd-openai-voice / api-key credential, without legacy account lookup or migration.

Reviewer-reproducible examples

• Open Voice settings with the default on-device chained configuration. Berd does not inspect the OpenAI Keychain credential.
• Select OpenAI transcription, OpenAI playback, or OpenAI Realtime. The corresponding settings load the shared credential status.
• Save or clear the shared key. Every mounted OpenAI voice surface refreshes to the new status, while simultaneous mount reads share one in-flight request.

[morgmart]

🤖 Automated code review

Engineering found one blocking credential-refresh race. The supplied GitHub evidence is structurally valid: Semgrep, zizmor, DCO, clean-room install, and Linux Rust checks passed, while frontend and macOS/Windows Rust checks were in progress when captured; required checks still govern merge readiness.

Deterministic publication result: 1 blocking and 0 non-blocking inline finding(s) publishable; 0 duplicate(s) suppressed; 0 blocking screenshot-evidence requirement(s) in this review body.

[morgmart]

🤖 Automated code review

Engineering completed a fresh static review of the full exact PR comparison and found no publishable issues. The previously reported credential-refresh race is fixed at this head and its resolved thread has a substantive human reply. Supplied GitHub evidence is structurally valid, and all captured check runs completed successfully; required checks still govern merge readiness.

Deterministic publication result: 0 blocking and 0 non-blocking inline finding(s) publishable; 0 duplicate(s) suppressed; 0 blocking screenshot-evidence requirement(s) in this review body.

Pending checks: 1 check(s) are not complete.

This approval reflects the completed code review only; merge readiness remains governed by the repository's required checks.