merge: upstream/dev into observer-firmware-dev (v1.17.1)

Picks up upstream MeshCore 1.17.1.

Notable upstream content:
- 1.17.1 version/build-date bump in the example MyMesh headers.
- nRF52: combine radio entropy with CC310 RNG.
- Companion FEM prefs: load/save of fem_ properties commented out until they
  can be set from the client.
- Scoped reply routing: replies no longer dropped when flood.max.unscoped is
  low (RoutingPolicy + unit tests).
- nRF52 unused-pin sweep (T1, T-Echo Lite, MeshPocket).

No conflicts.

examples/simple_sensor/SensorMesh.h

@@ -34,11 +34,11 @@
 #define PERM_RECV_ALERTS_HI    (1 << 7)   // high priority alerts
 
 #ifndef FIRMWARE_BUILD_DATE
-  #define FIRMWARE_BUILD_DATE   "9 Aug 2026"
+  #define FIRMWARE_BUILD_DATE   "14 Aug 2026"
 #endif
 
 #ifndef FIRMWARE_VERSION
-  #define FIRMWARE_VERSION   "v1.17.0"
+  #define FIRMWARE_VERSION   "v1.17.1"
 #endif
 
 #define FIRMWARE_ROLE "sensor"