- GET /api/candles accepts ?chartId= with fallback to most recent chart
- GET /api/annotations accepts ?chartId= with fallback to most recent chart
- POST /api/annotations now requires chart_id in request body
- GET /api/export accepts ?chartId= to scope exported annotations
- DELETE /api/annotations supports optional chartId scoping
- POST /api/upload now creates a chart named from the CSV filename
- Duplicate names get numeric suffix (e.g., btc-daily-2)
- Candles inserted with chart_id instead of replacing all data
- Response includes chart id and name
- Add charts table with id, name (unique), created_at
- Add chart_id FK to candles table with composite unique on (chart_id, time)
- Add chart_id FK to annotations table
- Custom migration handles existing data: creates 'Imported Data' chart and backfills chart_id
- Recreates tables for NOT NULL constraint (SQLite limitation)
