Compile fails due to user_btn not declared in board target.
Fixes:
- Add MomentaryButton declaration for user_btn in variants/xiao_nrf52/target.cpp
- Add momentary button helper include in variants/xiao_nrf52/target.h
- Add extern linkage for MomentaryButton -> user_btn in variants/xiao_nrf52/target.h
Without ROOM_PASSWORD the guest password defaults to empty, and a client
sending a blank password is granted read+write access (can post). Every
other board's room_server env sets ROOM_PASSWORD; the ThinkNode M6 and M1
were the only two shipping an open room. Default them to "hello" to match
the rest of the tree; operators can still change it at runtime with
'set guest.password'.
The M6 is the only board whose simple_repeater env ships with MESH_DEBUG=1
and GPS_NMEA_DEBUG=1 enabled. MESH_DEBUG=1 adds a 5-second boot delay
(examples/simple_repeater/main.cpp) plus verbose per-packet serial prints on
the hot RX/TX path; GPS_NMEA_DEBUG=1 echoes every GPS UART character to the
serial console (MicroNMEALocationProvider.h). Every sibling repeater env
(M1, M3, t1000-e, RAK, Heltec) ships these off, and the M6 room_server env
in this same file already has them commented. Comment them out to match.
External watchdog support was added (but never merged) for MeshTower V1. The update's V2's #defines to follow the conventions set there and piggy back off the support already written for V1.
GPS support was implemented incorrectly for the ThinkNode M3. The reset
pin was being driven when it should be left floating for this unit. The
enable pin also wasn't being picked up by `MicroNMEALocationProvider`
because of a mismatch in constant naming conventions. I did a general
cleanup of the GPS and ThinkNode M3 bring-up code so that constant names
line up and "*_ACTIVE" constants are used consistently vs hardcoding
`HIGH`/`LOW`. After making these changes, serial data immediately starts
streaming in from the NMEA on boot and GPS detection just works.
LED handling was also not quite right for the ThinkNode M3. The LoRa TX
LED was being driven high to turn it on when it should actually be
driven low. I changed the code to use the `LED_STATE_ON` constant and
also added a little code to the shutdown path to properly make sure that
all LEDs are turned off.
Tested and confirmed working on real hardware.
Resolves both #1864 and #2879.
