Integrate transcription language selection with local recorder fixes

[karansinghgit]

Summary

• cherry-pick the transcription language feature from Add transcription language selection and fix app launch UX #36 without taking the launch-policy changes
• add the settings language selector and mini-recorder quick picker for Whisper transcription language
• keep local follow-up work for the recorder pipeline and separate dev app workflow

Details

• cherry-picked from Add transcription language selection and fix app launch UX #36: 728ceb1 and 3c288c4
• intentionally excluded from Add transcription language selection and fix app launch UX #36: b44d8fd and 7432809
• includes local follow-up commit: 0f4eb24

Verification

• xcodebuild -project speaktype.xcodeproj -scheme speaktype -configuration Debug -destination 'generic/platform=macOS' build -quiet

Notes

• this supersedes the language-selection portion of Add transcription language selection and fix app launch UX #36 while preserving control over the rest of the integration work