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>

test/mocks/Arduino.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <cstdint>
+#include <cstdlib>
+#include <cmath>
+#include "Stream.h"
+
+inline uint32_t g_mock_millis = 0;
+
+using std::isnan;
+
+inline uint32_t millis() {
+  return g_mock_millis;
+}
+
+inline void delay(uint32_t ms) {
+  g_mock_millis += ms;
+}