v0.8.0: Face Blur Export + Media Fixes

What's New

Face Blur Export (Mission Critical)

• Blur unidentified faces during export — protects privacy by Gaussian-blurring all faces except tagged identities
• Video support — frame-by-frame face detection with downscaled detection (0.25x) for performance, ffmpeg pipe-based I/O preserving audio
• Export dialog toggle — new Switch UI component to enable/disable face blurring with progress streaming
• Identity-aware — faces matching tagged people (via embedding cosine similarity) are kept unblurred

Media Display Fixes

• EXIF orientation — phone photos now display correctly (was showing 0 faces due to missing exif_transpose())
• Video support — falls back to FFMPEG plugin when pyav unavailable
• HEIC/HEIF preview — generates JPEG previews since browsers can't render HEIC natively

Technical

• New blur_export sidecar command + Rust Tauri command with streaming progress events
• Switch and Label UI components (Base UI)
• 18 sidecar tests passing
• Scan cache versioning for automatic invalidation