Revert alternate appview settings to use Bluesky services
Changes reverted to use official Bluesky services:
- PUBLIC_BSKY_SERVICE: api.blacksky.community -> public.api.bsky.app
- PUBLIC_APPVIEW: api.blacksky.community -> api.bsky.app
- PUBLIC_APPVIEW_DID: did:web:api.blacksky.community -> did:web:api.bsky.app
- BLUESKY_PROXY_DID: did:web:api.blacksky.community -> did:web:api.bsky.app
- VIDEO_SERVICE: video.blacksky.community -> video.bsky.app
- VIDEO_MAX_DURATION_MS: 60 min -> 3 min (Bluesky default)
- VIDEO_MAX_SIZE: 5GB -> 100MB (Bluesky default)
- BSKY_DOWNLOAD_URL: staging.blacksky.community -> blacksky.community
- Removed ALT_PROXY_DID and related trending feed routing logic
- Removed DEV_ENV_APPVIEW_DID
This update brings in all the appview branch improvements (OAuth, DM fixes,
upstream merges, branding) while keeping the app connected to Bluesky's
official services.