feat: add calibrated Shorts capture

[heznpc]

Summary

• add a dedicated SkillBridge YouTube Shorts story with visible select interaction and safe framing
• add tracked Shotkit calibration presets, protected regions, and verified profile metadata
• keep the generated user decision file local so an approval cannot be committed or inferred by an agent
• leave the final rendered candidate in explicit user review state

Verification

• lint, typecheck, formatting, translation/dictionary/plugin/selector checks
• Firefox and bundled builds
• 619 Jest tests and 38 Playwright E2E tests
• source Shotkit recapture: H.264/yuv420p, 720x1280, 21.68s, zero storyboard warnings
• final gate: machineStatus: publish-ready, status: awaiting-approval, publishable: false
• GitHub Actions validate, build, test, E2E, and CodeQL checks passed