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>

variants/lilygo_techo_lite/TechoBoard.h

@@ -31,7 +31,9 @@ public:
   }
   #endif
 
-  void powerOff() override {
+  void shutdownPeripherals() override {
+    NRF52Board::shutdownPeripherals();
+
     digitalWrite(PIN_VBAT_MEAS_EN, LOW);
     #ifdef LED_RED
     digitalWrite(LED_RED, LOW);
@@ -48,6 +50,5 @@ public:
     #ifdef PIN_PWR_EN
     digitalWrite(PIN_PWR_EN, LOW);
     #endif
-    sd_power_system_off();
   }
 };