Wire ADS-B end to end: secondary-sdr container running dump1090

node-26#9. New secondary-sdr-container claims the node's SECOND physical
SDR (RTL-SDR index 1 — op25 always claims index 0; no serial-based binding
yet, same gap op25 itself has). Its control API (start/stop/status/data,
mirroring op25_controller.py) launches dump1090 in adsb mode and exposes
the decoded aircraft.json snapshot; AIS mode 400s until it's wired next.

edge-node: on_config_push starts/stops it when secondary_sdr_mode changes,
lifespan resumes it after a restart if already configured, and a new
telemetry_uplink_loop polls its /secondary/data every 10s and POSTs
non-empty snapshots to C2's new /telemetry/adsb (same bearer-key pattern
call_recorder.py already uses for audio upload).

UNVERIFIED: this container has not been built or run against real hardware
in this session (sandboxed authoring machine, no docker) — dump1090's
--write-json field names are believed correct from its docs but not
confirmed against a real capture. Build + hardware smoke test before this
reaches a real node.

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

secondary-sdr-container/app/routers/secondary_controller.py

@@ -0,0 +1,40 @@
+from fastapi import APIRouter, HTTPException
+from pydantic import BaseModel
+
+from internal import decoder_control
+from internal.logger import create_logger
+
+LOGGER = create_logger(__name__)
+
+
+class StartBody(BaseModel):
+    mode: str  # adsb | ais
+
+
+def create_secondary_router():
+    router = APIRouter()
+
+    @router.post("/start")
+    async def start(body: StartBody):
+        try:
+            ok = decoder_control.start(body.mode)
+        except ValueError as e:
+            raise HTTPException(status_code=400, detail=str(e))
+        if not ok:
+            raise HTTPException(status_code=500, detail="Failed to start secondary SDR decoder")
+        return {"status": f"secondary SDR started ({body.mode})"}
+
+    @router.post("/stop")
+    async def stop():
+        decoder_control.stop()
+        return {"status": "secondary SDR stopped"}
+
+    @router.get("/status")
+    async def get_status():
+        return decoder_control.status()
+
+    @router.get("/data")
+    async def get_data():
+        return decoder_control.data()
+
+    return router