GET /events.json with cursor-based pagination and filtering:
- Filter by adapter, category, since/until, region bbox
- Cursor pagination via (time DESC, id DESC) ordering
- Returns events with GeoJSON geometry parsed as objects
- Validation returns 400 with clear error messages
Migration 014 adds composite index for efficient pagination.
Tests: 17 new tests covering filters, pagination, validation.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
