feat(player): add AutoSync glass bubble notifications and secondary language fallback

[test01203]

Summary

Enhances the subtitle AutoSync engine with modern glass HUD notifications, secondary language fallback, and sticky user subtitle selection.

Key Changes

1. Glass Bubble Notifications (הודעות בועת זכוכית):

   • Modern frosted-glass HUD toast (AutoSyncBubbleToastHost & AutoSyncBubbleToast) floating in the player's top-start corner.
   • Non-intrusive backdrop blur with specular gradient borders, animated spinner during fingerprinting/alignment, green checkmark droplet on sync success, and animated offset adjustments.
   • Replaces generic Android Toasts with TV-optimized, smooth fade/slide transitions that automatically dock when player controls toggle.
   • User toggle in Settings under Subtitle AutoSync.

2. Secondary Preferred Subtitle Language Fallback:

   • If AutoSync or automated matching fails to find or synchronize a match in the primary subtitle language, the engine automatically attempts synchronization against the user's configured secondary subtitle language before falling back to audio delay shifting.
   • Seamlessly integrates with the existing subtitle scoring and alignment pipelines.

3. Preserve User Subtitle Selection:

   • Explicit manual subtitle selections made by the user are preserved and will not be overridden by background AutoSync runs during playback.

[silentbil]

Thanks for putting this together! I went through the changes to the AutoSync / subtitle matching flow, and I'd prefer not to proceed with this PR, because of the risk to a feature that's working well right now. A few specifics:

1. Secondary-language fallback can leave the scan stuck.
The fallback calls findBestSubtitleMatch(scanLang = secondaryLang) from inside the running scan. At that point the scan hasn't ended yet: isFindingBestMatch is still true until selectLastResort() / endMatch() run. So the nested call returns immediately on its guard. Then return@launch skips the audio-sync fallback and the last-resort pick, and "Adjusting subtitles…" stays on screen for the rest of that playback, blocking further scans. This would hit anyone with a secondary language set whenever the primary language isn't verified.

2. Secondary-language references in audio sync.
englishCandidates() feeds the references that the recognised speech is matched against, and that matching is text-based on English. Subtitles in another language can't match the recognised words, and they compete for the same few slots (PREFETCH_REFERENCES = 2, MAX_REFERENCES = 4), so they can push out the English references that actually make the sync work.

3. "Preserve User Subtitle Selection".
I couldn't find any change for this in the diff. It's also already handled on main: a manual pick sets hasManualSubtitleSelection / userPickedSubtitle, and both auto-selection and audio sync back off when they're set.

Thanks again for the effort and interest in this part of the app!