feat(live-atc): forward aircraft position, un-throttle bridge polling

- NormalizedTelemetry carries lat/lon (0/0 no-GPS guard, position in the
  change-detection signature) so the backend can derive distance triggers
- bridge polling moves from setInterval to a Worker tick: with the sim in the
  foreground the /live-atc tab is backgrounded and Chrome throttles plain
  intervals to ~1/min — telemetry-driven ATC lagged behind the silence fallback

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/shared/bridgeTelemetry.test.ts

@@ -38,6 +38,26 @@ test('normalizeBridgeTelemetry returns null for non-object input', () => {
   assert.equal(normalizeBridgeTelemetry(null), null)
 })
 
+test('normalizeBridgeTelemetry forwards the position', () => {
+  const result = normalizeBridgeTelemetry({
+    PLANE_ALTITUDE: 3500,
+    PLANE_LATITUDE: 50.02671,
+    PLANE_LONGITUDE: 8.55835,
+  })
+  assert.equal(result?.lat, 50.02671)
+  assert.equal(result?.lon, 8.55835)
+})
+
+test('normalizeBridgeTelemetry drops the 0/0 no-GPS default position', () => {
+  const result = normalizeBridgeTelemetry({
+    PLANE_ALTITUDE: 3500,
+    PLANE_LATITUDE: 0,
+    PLANE_LONGITUDE: 0,
+  })
+  assert.equal(result?.lat, undefined)
+  assert.equal(result?.lon, undefined)
+})
+
 test('telemetrySignature is stable under sub-threshold jitter', () => {
   const a = telemetrySignature({ altitude_ft: 3500, ias_kts: 140, on_ground: false })
   const b = telemetrySignature({ altitude_ft: 3540, ias_kts: 141, on_ground: false })
@@ -49,3 +69,9 @@ test('telemetrySignature changes on a meaningful altitude change', () => {
   const b = telemetrySignature({ altitude_ft: 4200, on_ground: false })
   assert.notEqual(a, b)
 })
+
+test('telemetrySignature changes as the aircraft moves (~0.6 nm)', () => {
+  const a = telemetrySignature({ altitude_ft: 3500, lat: 50.0, lon: 8.0 })
+  const b = telemetrySignature({ altitude_ft: 3500, lat: 50.02, lon: 8.0 })
+  assert.notEqual(a, b)
+})