Mixed-media playback takes shape

The simulator is finally exercising something closer to my real photo library instead of a tidy set of fake images. Photos, videos, and Live Photo-style pairs can share one rotation, and the rough edges in color, sequencing, and random order are becoming visible enough to fix.

Changelog

• Local Samples videos with HDR-style color metadata now render with SDR-safe color in the Apple TV simulator instead of appearing washed out.
• The simulator Local Samples fix preserves existing SDR video, photo, and black-background aspect-fit behavior.
• Local Samples videos now continue to the next slideshow item as soon as playback ends instead of lingering on the final frame.
• Unambiguous local Live Photo-style exports now play their motion and settle on the matching still image.
• Random playback now starts a fresh shuffled order each time Settings is closed and applied.
• Chronological playback orders continue to behave predictably.
• Local Samples simulator launches now verify that local media was copied into the app bundle before install.
• The Local Samples no-media screen now shows aggregate bundle and eligibility counts so empty installs are easier to diagnose.
• Local Samples HDR-like videos now use direct Apple video playback again instead of the custom simulator rendering path that could turn them black.
• Local Samples validation now reports aggregate HDR-like video counts while keeping private media details out of logs and diagnostics.