GET /events: Full page with filter form, table, and Leaflet map
GET /events/rows: HTMX fragment for table updates
Features:
- Filterable by adapter, category, time range, region bbox
- Cursor-based pagination with Next button
- Leaflet map showing event geometries
- Click/hover row highlights geometry on map
- Draw rectangle on map to filter by region
- Validation errors shown as banner, not 400
- Events link added to nav between Adapters and Streams
Refactored events query into shared helper for JSON and HTML routes.
Tests: 14 new tests covering filters, fragments, geometry handling.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
