Replace raw SQL CREATE TABLE statements with proper SeaORM migration
system. This eliminates verbose SQL logs on startup and provides
proper migration tracking and rollback support.
Changes:
- Add sea-orm-migration dependency and migration crate
- Create initial migration (m20250101_000001) with all 8 tables
- Update storage::init() to only connect to database
- Run migrations automatically in main.rs on startup
- Remove unused detect_backend() function and imports
The migration system properly handles both SQLite and PostgreSQL
backends with appropriate type handling (e.g., BIGSERIAL vs INTEGER
for auto-increment columns).
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
