Implement a first-class schema version system with the following components:
- schema_versions table (SQLite) tracking applied migrations
- Numbered migration files (001_initial.sql, 002_feature_tables.sql)
- MigrationRegistry for version validation and pending migration detection
- Startup: read current version → apply pending migrations → record latest
- Refuse to start if DB version > binary version (SchemaVersionAhead error)
Acceptance criteria met:
- First run creates schema at version 001
- Second run is a no-op (single SELECT for version check)
- Store version > binary version fails with SchemaVersionAhead error
- Migration metadata structure is backend-agnostic (shared by SQLite/Redis)
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
