fix: Bus event first ingestion skips historical events due to high-water mark

[evansenter]

Problem

The ingest_bus_events() function uses MAX(event_id) from the bus_events table as a high-water mark. On the first run, it applies a timestamp-based cutoff (days=7 default), ingests only recent events, then sets the high-water mark to the latest event ID. All subsequent runs — even with days=365 — only look for events with id > high_water_mark, permanently skipping older events.

This was discovered immediately after merging #107: startup ingestion with days=7 ingested 109 of 2,696 events, and a follow-up days=365 call found nothing new.

Workaround

Clear bus_events and re-ingest:

storage.execute_write('DELETE FROM bus_events')
ingest_bus_events(storage, days=365)

Fix options

1. Use a larger startup default — Change startup ingestion to days=365 so first run captures full history
2. Separate first-run logic — When bus_events is empty, ignore the days parameter and ingest everything
3. Always use timestamp cutoff — Don't use high-water mark at all; rely on INSERT OR IGNORE for dedup (slower but correct)

Option 2 seems cleanest: if the table is empty, ingest everything regardless of days.