Add core services and widgets for Streamable video playback: - StreamableService: API client for fetching video URLs - Extracts shortcodes from URLs (handles /e/ format) - 5-minute URL caching to reduce API calls - Singleton Dio instance with 10s timeouts - Handles protocol-relative URLs - FullscreenVideoPlayer: Immersive video playback - Swipe-to-dismiss gesture (vertical drag) - Tap to play/pause - Fade out background during swipe - Lifecycle-aware (pauses on app background) - MinimalVideoControls: Clean scrubber interface - Progress bar with seek support - Current time / total duration display - Minimal, non-intrusive design 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>