Remove all local level storage concepts and load levels exclusively from
Supabase cloud. Simplifies LevelRegistry from 380+ lines to ~50 lines.
Uses CloudLevelEntry directly throughout the codebase instead of wrapper
types like LevelDirectoryEntry.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
