Add explicit capture presets for social video output

[sfegette]

Summary

The current capture path uses .high plus the active camera format and crop math, but does not appear to explicitly define a social-video-oriented recording profile.

Why this matters

For Reels / TikTok / Shorts workflows, predictable output matters more than “whatever the active camera format currently is.” Right now there is no obvious policy for:

• target resolution
• frame rate
• stabilization
• orientation / mirroring
• exposure / white-balance consistency
• audio sample rate strategy

Suggested direction

• Define explicit output presets, especially a vertical 1080x1920 @ 30fps path
• Decide on intentional front-camera mirroring behavior for preview vs output
• Evaluate stabilization options where hardware supports them
• Consider standardizing audio capture/output settings for creator workflows
• Document the chosen output policy in README / product docs

Relevant code

• Capture/CaptureManager.swift lines 302-306
• Capture/CaptureManager.swift lines 409-478
• repo-wide search found no explicit orientation/mirroring/stabilization handling

Acceptance criteria

• At least one social-video preset is explicit and reproducible
• Orientation/mirroring behavior is intentional rather than implicit
• Output is more predictable across devices and camera formats