Wire ADS-B end to end: telemetry ingestion + live map overlay

node-26#9. Adds POST /telemetry/adsb (node-key authed via
require_node_service_or_firebase_token) that upserts one Firestore doc per
icao into a new `aircraft` collection, org_id stamped from the reporting
node the same way upload.py defensively stamps `calls`. firestore.rules
gets a matching docInMyOrg()-gated read rule.

Frontend: useAircraft() mirrors useNodes()'s onSnapshot pattern, filtering
docs older than 2 minutes client-side since nothing prunes a stale aircraft
doc server-side yet. MapView gets an opt-in "Aircraft" overlay (unchecked
by default, like the weather radar layer) rendering a rotated plane glyph
per sighting.

Unverified via typecheck — no Node.js/npm on this authoring box yet (see
CLAUDE.md Testing reality). Server side is pytest-covered (test_telemetry.py).

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

drb-frontend/components/MapView.tsx

@@ -15,6 +15,7 @@ import L from "leaflet";
 import type { CallRecord, IncidentRecord, NodeRecord, NodeStatus } from "@/lib/types";
 import { isKnownSeverity, SEVERITY_COLORS, SEVERITY_LABEL, type Severity } from "@/lib/severity";
 import { MachineOutputNotice } from "@/components/ui/MachineOutputNotice";
+import { useAircraft } from "@/lib/useAircraft";
 
 // ── Leaflet icon fix ──────────────────────────────────────────────────────────
 delete (L.Icon.Default.prototype as unknown as Record<string, unknown>)._getIconUrl;
@@ -90,6 +91,40 @@ function nodeIcon(status: NodeStatus): L.DivIcon {
   });
 }
 
+// ── Aircraft icon — node-26#9 second-SDR ADS-B overlay ────────────────────────
+function aircraftIcon(trackDeg: number | null): L.DivIcon {
+  const size = 16;
+  const rotation = trackDeg ?? 0;
+  return L.divIcon({
+    className: "",
+    html: `<div style="width:${size}px;height:${size}px;transform:rotate(${rotation}deg)"><svg width="${size}" height="${size}" viewBox="0 0 24 24" fill="var(--accent)" stroke="var(--surface)" stroke-width="1"><path d="M12 2 L15 11 L22 15 L15 15.5 L14 21 L17 22.5 L12 21.5 L7 22.5 L10 21 L9 15.5 L2 15 L9 11 Z"/></svg></div>`,
+    iconSize: [size, size],
+    iconAnchor: [size / 2, size / 2],
+  });
+}
+
+function AircraftLayer() {
+  const { aircraft } = useAircraft();
+  return (
+    <>
+      {aircraft
+        .filter((a) => a.lat != null && a.lon != null)
+        .map((a) => (
+          <Marker key={a.icao} position={[a.lat as number, a.lon as number]} icon={aircraftIcon(a.track_deg)}>
+            <Popup minWidth={160}>
+              <div className="space-y-1">
+                <div className="font-semibold">{a.callsign || a.icao}</div>
+                <div className="text-xs text-ink-muted">ICAO {a.icao}</div>
+                {a.altitude_ft != null && <div className="text-xs">Altitude: {Math.round(a.altitude_ft)} ft</div>}
+                {a.ground_speed_kt != null && <div className="text-xs">Speed: {Math.round(a.ground_speed_kt)} kt</div>}
+              </div>
+            </Popup>
+          </Marker>
+        ))}
+    </>
+  );
+}
+
 function nodeFanIcon(members: NodeRecord[]): L.DivIcon {
   const n = members.length;
   const CARD = 13;
@@ -577,6 +612,13 @@ export default function MapView({ nodes, activeCalls, incidents = [], calls = []
             </FeatureGroup>
           </LayersControl.Overlay>
 
+          {/* Overlay: Aircraft — node-26#9 second-SDR ADS-B live snapshot, opt-in */}
+          <LayersControl.Overlay name="Aircraft">
+            <FeatureGroup>
+              <AircraftLayer />
+            </FeatureGroup>
+          </LayersControl.Overlay>
+
           {/* Overlay: Weather Radar — NEXRAD via Iowa Env Mesonet; key forces remount on refresh */}
           <LayersControl.Overlay name="Weather Radar">
             <TileLayer