Merge upstream/main (v1.16.0) into wio-unified

Merge 254 upstream commits. Highlights relevant to the Wio fork: native
NRF52 companion power-saving (sleep when !hasPendingWork), preamble 16->32
for SF<9, generic sensor-registration model, CMD_SEND_RAW_PACKET, isEink()
display abstraction, KEEP_DISPLAY_ON_USB, contacts-sync/transient fixes.

Conflicts resolved (11 files):
- buzzer.h/.cpp: keep NRF52 include guard + our begin()->startup(); fold in
  upstream doc comment.
- platformio (wio + eink): keep our slim env layout, add upstream kiss_modem
  env (+ debug_tool=stlink on eink ble).
- GxEPDDisplay.h: take upstream isEink() override.
- EnvironmentSensorManager.h: take upstream's wider #if guard.
- DataStore.cpp: take upstream saveContacts(filter) signature, keep our
  ::openWrite (member openWrite would shadow the global 2-arg overload).
- main.cpp: keep our watchdog init + add board.onBootComplete(); adopt
  upstream's `if(!hasPendingWork()) sleep` loop.
- MyMesh.h: version -> v1.16-solo.0, build date 6 Jun 2026.
- MyMesh.cpp: keep both CMD codes (SCREENSHOT 66 + RAW_PACKET 65), both field
  inits, both handlers, our screenshot fns + upstream saveContacts/save_filter,
  upstream hasPendingWork() + our MyMeshBot include.
- UITask.cpp: keep our solo splash/clock page/snprintf/buzzer init; merge
  auto-off (+ opt-in KEEP_DISPLAY_ON_USB); merge low-batt shutdown (our EMA +
  prefs threshold + upstream's !isExternalPowered() guard and eink-aware delay).

Post-merge drift fixes (upstream API/architecture changes, not conflicts):
- applyTxPower(): radio_set_tx_power() removed upstream -> radio_driver.setTxPower().
- Sensor refactor dropped the per-sensor *_initialized flags our
  getAvailableLPPTypes() relied on; removed that override and the SENSORS page
  now derives available LPP types from the populated sensors_lpp buffer.

README kept ours via .gitattributes merge=ours. Builds verified on all 5 Wio
envs (dual, eink dual, radio_ble, dual_dev, eink_dual_dev). Not yet
hardware-verified.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

variants/wio-tracker-l1-eink/platformio.ini

@@ -60,6 +60,7 @@ lib_deps = ${nrf52_base.lib_deps}
 [env:WioTrackerL1Eink_companion_radio_ble]
 extends = WioTrackerL1Eink
 extra_scripts = post:create-uf2.py
+debug_tool=stlink
 
 ; Dual BLE+USB
 [env:WioTrackerL1Eink_companion_dual]
@@ -74,3 +75,8 @@ extends = WioTrackerL1Eink
 build_flags = ${WioTrackerL1Eink.build_flags}
   -D DUAL_SERIAL=1
   -D ENABLE_SCREENSHOT
+
+[env:WioTrackerL1Eink_kiss_modem]
+extends = WioTrackerL1Eink
+build_src_filter = ${WioTrackerL1Eink.build_src_filter}
+  +<../examples/kiss_modem/>