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/m5stack_cardputer_adv/platformio.ini

@@ -108,7 +108,7 @@ build_flags =
   -D DUAL_SERIAL=1
   -D OFFLINE_QUEUE_SIZE=256
   -D FIRMWARE_SOLO_BUILD=1
-  -D MESHCORE_VERSION='"1.16"'
+  -D MESHCORE_VERSION='"1.17"'
   -D UI_SENSORS_PAGE=1
   -D ENABLE_SCREENSHOT
   ; misc-fixed 6x9 font (full Latin/Greek/Cyrillic), same as the Wio L1/Heltec