Merge upstream companion-v1.17.0 (CAD) into power-saving

Adopts hardware Channel Activity Detection (wired into
RadioLibWrapper::isChannelActive() alongside our RSSI-threshold check
and RX duty-cycle power-save), MCU temperature telemetry, LR2021
standby workaround, DISPLAY_SCALE/FLIP overrides, NRF52Board
shutdownPeripherals() refactor, and misc upstream fixes.

Declines upstream's ConfigSerializer-based NodePrefs rewrite,
MultiSerialInterface/interface_manager, and UIColor palette system —
each would have broken large parts of the Solo-specific feature set
(NodePrefs fields, per-variant single serial_interface, enum-based
DisplayDriver::Color). Flagged as candidate follow-up migrations, not
permanent no's.

Also fixes several pre-existing bugs surfaced while chasing silent
merge breaks (stale newMsg() override signature in ui-tiny/ui-orig,
dead UIEventType::newContactMessage case, missing ContactsIterator
init), bumps FIRMWARE_VERSION/MESHCORE_VERSION to 1.17, and fixes a
missing <cstdlib> include that broke the native ConfigSerializer unit
tests.

Verified via 13+ pio run builds across ESP32/nRF52, all 3 companion UI
variants, and 7 display drivers, plus the full native unit test suite
(33/33 passing).

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

examples/simple_sensor/SensorMesh.cpp

@@ -323,6 +323,9 @@ uint32_t SensorMesh::getDirectRetransmitDelay(const mesh::Packet* packet) {
 int SensorMesh::getInterferenceThreshold() const {
   return _prefs.interference_threshold;
 }
+bool SensorMesh::getCADEnabled() const {
+  return _prefs.cad_enabled;
+}
 int SensorMesh::getAGCResetInterval() const {
   return ((int)_prefs.agc_reset_interval) * 4000;   // milliseconds
 }
@@ -707,7 +710,6 @@ SensorMesh::SensorMesh(mesh::MainBoard& board, mesh::Radio& radio, mesh::Millise
   set_radio_at = revert_radio_at = 0;
 
   // defaults
-  memset(&_prefs, 0, sizeof(_prefs));
   _prefs.airtime_factor = 1.0;
   _prefs.rx_delay_base =   0.0f;  // turn off by default, was 10.0;
   _prefs.tx_delay_factor = 0.5f;   // was 0.25f
@@ -726,11 +728,13 @@ SensorMesh::SensorMesh(mesh::MainBoard& board, mesh::Radio& radio, mesh::Millise
   _prefs.disable_fwd = true;
   _prefs.flood_max = 64;
   _prefs.interference_threshold = 0;  // disabled
+  _prefs.cad_enabled = 0;             // hardware CAD before TX (off by default; 'set cad on')
 
   // GPS defaults
   _prefs.gps_enabled = 0;
   _prefs.gps_interval = 0;
   _prefs.advert_loc_policy = ADVERT_LOC_PREFS;
+  _prefs.radio_fem_rxgain = 1;
 
   memset(default_scope.key, 0, sizeof(default_scope.key));
 }
@@ -766,6 +770,7 @@ void SensorMesh::begin(FILESYSTEM* fs) {
 
   radio_driver.setParams(_prefs.freq, _prefs.bw, _prefs.sf, _prefs.cr);
   radio_driver.setTxPower(_prefs.tx_power_dbm);
+  board.setLoRaFemLnaEnabled(_prefs.radio_fem_rxgain);
 
   updateAdvertTimer();
   updateFloodAdvertTimer();

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   "6 Jun 2026"
+  #define FIRMWARE_BUILD_DATE   "9 Aug 2026"
 #endif
 
 #ifndef FIRMWARE_VERSION
-  #define FIRMWARE_VERSION   "v1.16.0"
+  #define FIRMWARE_VERSION   "v1.17.0"
 #endif
 
 #define FIRMWARE_ROLE "sensor"
@@ -120,6 +120,7 @@ protected:
   uint32_t getRetransmitDelay(const mesh::Packet* packet) override;
   uint32_t getDirectRetransmitDelay(const mesh::Packet* packet) override;
   int getInterferenceThreshold() const override;
+  bool getCADEnabled() const override;
   int getAGCResetInterval() const override;
   void onAnonDataRecv(mesh::Packet* packet, const uint8_t* secret, const mesh::Identity& sender, uint8_t* data, size_t len) override;
   int searchPeersByHash(const uint8_t* hash) override;

examples/simple_sensor/UITask.cpp

@@ -41,7 +41,8 @@ void UITask::begin(NodePrefs* node_prefs, const char* build_date, const char* fi
   }
 
   // v1.2.3 (1 Jan 2025)
-  sprintf(_version_info, "%s (%s)", version, build_date);
+  snprintf(_version_info, sizeof(_version_info), "%s (%s)", version, build_date);
+  free(version);
 }
 
 void UITask::renderCurrScreen() {

examples/simple_sensor/main.cpp

@@ -58,6 +58,10 @@ void setup() {
 
   board.begin();
 
+#ifdef HAS_EXTERNAL_WATCHDOG
+  external_watchdog.begin();
+#endif
+
 #ifdef DISPLAY_CLASS
   if (display.begin()) {
     display.startFrame();
@@ -147,4 +151,7 @@ void loop() {
   ui_task.loop();
 #endif
   rtc_clock.tick();
+#ifdef HAS_EXTERNAL_WATCHDOG
+  external_watchdog.loop();
+#endif
 }