build: publish mobile beta 1.9.0-beta.2

[Priveetee]

Summary

• Prepare beta version 1.9.0-beta.2 with version code 10825.
• Fix the beta.1 regression that removed channel avatars from the layout once they finished loading.
• Animate video thumbnails with the same pulsing skeleton as avatars, on video cards, related videos, continue watching, playlists, and horizontal cards.
• Tint the shared skeleton from the foreground color like the web client instead of the surface color, so the placeholder matches the shadcn look.

Verification

• 822 unit tests passed with no failures, plus lint, debug and release builds.
• Emulator checks on API 34: avatars render on the home feed, search results, and continue watching; the loading placeholders appear as pulsing grey blocks for both thumbnails and avatars, then the real images replace them; the network was throttled and the Coil cache cleared to reach the loading window.