Add ADS-B, AIS, and ALPR map layers with live CoT streaming (#36)

## Summary

- **ADS-B & AIS:** OpenSky and AISStream OSINT feeds upsert into the CoT store; tactical tracks still arrive via adsbcot/aiscot on `:8089`. Map clients subscribe via `GET /api/cot/stream` (SSE) with viewport bbox filtering and Air / Surface / Team layer toggles.
- **ALPR (Flock/OSM):** Toggleable license-plate reader layer sourced from OpenStreetMap, with SQLite cache, Overpass fallback, tiled viewport fetching, and clustered markers with direction cones.
- **Map performance:** Ring-based tile selection (fixes zoom-out crash), immutable tile cache, incremental marker sync, split cluster load/query, and padded SSE bbox to reduce reconnect churn.

## Docs

- `docs/tracking.md` — ADS-B/AIS accuracy tiers, freshness, self-hosted receivers, optional OSINT API keys
- `docs/map-and-cameras.md` — ALPR layer and map behavior updates

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Co-authored-by: Madison Grubb <madison@elastiflow.com>
Reviewed-on: #36

test/e2e/utils/server.js

@@ -35,7 +35,7 @@ export function ensureDevCerts() {
     console.log('[test] Generated .dev-certs/key.pem and .dev-certs/cert.pem')
   }
   catch (error) {
-    throw new Error(`Failed to generate dev certificates: ${error.message}`)
+    throw new Error(`Failed to generate dev certificates: ${error.message}`, { cause: error })
   }
 }