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/integration/shutdown.spec.js

@@ -1,27 +1,24 @@
 import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest'
+import { SHUTDOWN_TIMEOUT_MS } from '../../server/utils/constants.js'
 import { registerCleanup, graceful, initShutdownHandlers, clearCleanup } from '../../server/utils/shutdown.js'
 
 describe('shutdown integration', () => {
-  const testState = {
-    originalExit: null,
-    exitCalls: [],
-    originalOn: null,
-  }
+  /** @type {import('vitest').MockInstance} */
+  let exitSpy
+  /** @type {typeof process.on} */
+  let originalOn
 
   beforeEach(() => {
     clearCleanup()
-    testState.exitCalls = []
-    testState.originalExit = process.exit
-    process.exit = vi.fn((code) => {
-      testState.exitCalls.push(code)
-    })
-    testState.originalOn = process.on
+    exitSpy = vi.spyOn(process, 'exit').mockImplementation(() => {})
+    originalOn = process.on
   })
 
   afterEach(() => {
-    process.exit = testState.originalExit
-    process.on = testState.originalOn
+    exitSpy.mockRestore()
+    process.on = originalOn
     clearCleanup()
+    vi.useRealTimers()
   })
 
   it('initializes signal handlers', () => {
@@ -32,7 +29,6 @@ describe('shutdown integration', () => {
     initShutdownHandlers()
     expect(process.on).toHaveBeenCalledWith('SIGTERM', expect.any(Function))
     expect(process.on).toHaveBeenCalledWith('SIGINT', expect.any(Function))
-    process.on = testState.originalOn
   })
 
   it('signal handler calls graceful', async () => {
@@ -43,9 +39,10 @@ describe('shutdown integration', () => {
     initShutdownHandlers()
     const sigtermHandler = handlers.SIGTERM
     expect(sigtermHandler).toBeDefined()
-    await sigtermHandler()
-    expect(testState.exitCalls.length).toBeGreaterThan(0)
-    process.on = testState.originalOn
+    sigtermHandler()
+    await vi.waitFor(() => {
+      expect(exitSpy).toHaveBeenCalled()
+    })
   })
 
   it('signal handler handles graceful error', async () => {
@@ -59,18 +56,20 @@ describe('shutdown integration', () => {
     registerCleanup(async () => {
       throw new Error('Force error')
     })
-    await sigintHandler()
-    expect(testState.exitCalls.length).toBeGreaterThan(0)
-    process.on = testState.originalOn
+    sigintHandler()
+    await vi.waitFor(() => {
+      expect(exitSpy).toHaveBeenCalled()
+    })
   })
 
   it('covers timeout path in graceful', async () => {
+    vi.useFakeTimers()
     registerCleanup(async () => {
-      await new Promise(resolve => setTimeout(resolve, 40000))
+      await new Promise(resolve => setTimeout(resolve, SHUTDOWN_TIMEOUT_MS + 5_000))
     })
     graceful()
-    await new Promise(resolve => setTimeout(resolve, 100))
-    expect(testState.exitCalls.length).toBeGreaterThan(0)
+    await vi.advanceTimersByTimeAsync(SHUTDOWN_TIMEOUT_MS + 1)
+    expect(exitSpy).toHaveBeenCalledWith(1)
   })
 
   it('covers graceful catch block', async () => {
@@ -78,6 +77,6 @@ describe('shutdown integration', () => {
       throw new Error('Test error')
     })
     await graceful()
-    expect(testState.exitCalls.length).toBeGreaterThan(0)
+    expect(exitSpy).toHaveBeenCalled()
   })
 })