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

---------

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

test/nuxt/useCotStream.spec.js

@@ -0,0 +1,38 @@
+import { describe, it, expect, beforeEach, afterEach } from 'vitest'
+import { useCotLayers } from '../../app/composables/useCotLayers.js'
+
+describe('useCotLayers', () => {
+  beforeEach(() => {
+    localStorage.clear()
+  })
+
+  afterEach(() => {
+    localStorage.clear()
+  })
+
+  it('defaults all layers on', () => {
+    const { layers, layerQuery } = useCotLayers()
+    expect(layers.value).toEqual({ air: true, surface: true, ground: true })
+    expect(layerQuery.value).toBe('air,surface,ground')
+  })
+
+  it('toggles layers and persists to localStorage', () => {
+    const { layers, toggleLayer, layerQuery } = useCotLayers()
+    toggleLayer('air')
+    expect(layers.value.air).toBe(false)
+    expect(layerQuery.value).toBe('surface,ground')
+    const stored = JSON.parse(localStorage.getItem('kestrel-cot-layers'))
+    expect(stored.air).toBe(false)
+  })
+})
+
+describe('useCotStream helpers', () => {
+  it('layer query none when all off', () => {
+    localStorage.clear()
+    const { toggleLayer, layerQuery } = useCotLayers()
+    toggleLayer('air')
+    toggleLayer('surface')
+    toggleLayer('ground')
+    expect(layerQuery.value).toBe('none')
+  })
+})