[codex] Add video capture audio selector

[huntharo]

Summary

Adds audio controls to the video selector so users can choose whether a recording includes audio before recording starts.

What Changed

• Threaded recording audio capabilities through the region selector.
• Added video-only System audio and Microphone toggles to the area selector.
• Seeded toggles from settings.recording and persisted the latest choice.
• Added renderer coverage for submitting toggled capabilities.

Verification

• pnpm --filter @pwrsnap/desktop typecheck
• pnpm exec vitest run --config vitest.workspace.ts --project desktop-renderer apps/desktop/src/renderer/src/features/region/__tests__/RegionSelectorAudio.test.tsx apps/desktop/src/renderer/src/features/region/__tests__/region-math.test.ts

Note

A broad workspace Vitest invocation was attempted first, but this local checkout's Electron package reports Electron failed to install correctly, which breaks desktop-main suites before this change can be evaluated there.