- Convert numpy.int64 to Python int before passing to SQLAlchemy queries
- Prevents psycopg2.ProgrammingError: can't adapt type 'numpy.int64'
- Applied to get_candles(), get_span_annotations(), and get_point_annotations()
- All ML service database access tests now passing successfully
- Created scripts/migrate-sqlite-to-postgres.py as alternative to TypeScript version
- Handles all type conversions: timestamps, booleans, and JSONB fields
- Successfully migrated all 2,836 rows from SQLite to PostgreSQL
- Verified data integrity: all 6 tables migrated correctly
- Charts: 1, Candles: 2,592, Annotations: 4, Span annotations: 223
