## Summary
- Subsequent syncs (every 6h) now only process recent data instead of
re-syncing full history, reducing unnecessary API calls and database
writes
- Full sync still runs automatically on first connection and can be
forced anytime with `banking:sync --full`
- Centralizes `isFirstSync` logic in `SyncBankingConnectionJob` and
propagates the `fullSync` flag through the entire chain: Command →
`SyncAllBankingConnectionsJob` → `SyncBankingConnectionJob` → provider
services
## Changes by provider
- **Indexa Capital**: Skips portfolio entries older than the last
recorded balance date on incremental syncs (the API doesn't support date
filtering, so filtering is done client-side)
- **Binance**: Reuses stored `invested_amount` from the database on
subsequent syncs instead of fetching up to 2 years of deposit/withdrawal
history in 90-day windows
- **EnableBanking / Bitpanda**: Already minimal — no changes needed
## Testing
- Fixed 6 existing Binance tests to pass `isFirstSync: true` for
invested amount calculation
- Added 7 new tests covering incremental sync behavior, full sync
override, and `--full` flag propagation
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