Release 0.2.2: merge dev to main

[threehappypenguins]

VideoSphere 0.2.2

YouTube import: embed preview fallback

Fresh or recently processed YouTube videos (especially post-live VODs) often expose only DASH/HLS formats to yt-dlp, with no browser-streamable progressive MP4 for the trim editor. Import no longer hard-fails in that case.

Added

• Embed preview mode — When yt-dlp returns formats but none are browser-streamable, resolve succeeds with previewMode: 'embed' and the import modal uses YouTube’s IFrame Player for trim preview instead of the proxied HTML5 stream.
• YouTubeEmbedPreviewPlayer — Loads the YouTube IFrame API once per page and exposes previewAt / getCurrentTime for trim handle sync.
• NoBrowserStreamableFormatError — Typed signal for the DASH/HLS-only case; resolve maps it to embed fallback while other preview failures still return 502.

Changed

• Import trim UI (embed mode) — Smart cut is required and locked on; frame nudge buttons and live keyframe snapping are hidden; coarse jump-step controls remain.
• Resolve API — Successful direct preview responses now include previewMode: 'direct' explicitly.

Fixed

• Empty yt-dlp format lists — Treated as a real metadata failure (502), not embed fallback, so JS-challenge or auth failures are not masked as “processing” videos.
• Smart cut copy — Embed-mode helper text and tooltips now describe frame-accurate cuts after download instead of incorrectly saying cuts snap to keyframes.