Native MacOS hello world (#10309)

* Native MacOS hello world

* Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update variants/native/portduino/platformio.ini

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* fix: ensure null-termination in getSerialString() and handle len==0

Agent-Logs-Url: https://github.com/meshtastic/firmware/sessions/e5647919-2255-48ad-bcaa-7a2c2fdbf212

Co-authored-by: thebentern <9000580+thebentern@users.noreply.github.com>

---------

Co-authored-by: Jonathan Bennett <jbennett@incomsystems.biz>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

variants/native/portduino.ini

@@ -2,7 +2,7 @@
 [portduino_base]
 platform =
   # renovate: datasource=git-refs depName=platform-native packageName=https://github.com/meshtastic/platform-native gitBranch=develop
-  https://github.com/meshtastic/platform-native/archive/135b91e953db0b5f44d278f8ebd5b8d985fc03d8.zip
+  https://github.com/meshtastic/platform-native/archive/4ea5e09ac7d51a593e12ec7c1ebb6cd06745ce53.zip
 framework = arduino
 
 build_src_filter = 
@@ -37,25 +37,35 @@ lib_deps =
   # renovate: datasource=github-tags depName=Adafruit_BME680 packageName=adafruit/Adafruit_BME680
   https://github.com/adafruit/Adafruit_BME680/archive/refs/tags/2.0.6.zip
 
-build_flags =
+; Cross-platform build flags shared between native (Linux) and native-macos builds.
+; Anything Linux-only (libbluetooth, libgpiod, libi2c, /sys/class/gpio,
+; PORTDUINO_LINUX_HARDWARE, glibc-style _FORTIFY_SOURCE) goes in `build_flags`
+; instead. UDP multicast also lives there because the firmware's
+; UdpMulticastHandler.h unconditionally `#include <WiFi.h>` on non-NRF52
+; targets, which requires the framework's bundled WiFi shim that we
+; lib_ignore on macOS.
+build_flags_common =
   ${arduino_base.build_flags}
   -D ARCH_PORTDUINO
   -fPIC
-  -D_FORTIFY_SOURCE=2
-  -fstack-protector-all -Wstack-protector --param ssp-buffer-size=4
   -Isrc/platform/portduino
   -DRADIOLIB_EEPROM_UNSUPPORTED
-  -DPORTDUINO_LINUX_HARDWARE
-  -DHAS_UDP_MULTICAST=1
   -lpthread
-  -lstdc++fs
-  -lbluetooth
-  -lgpiod
   -lyaml-cpp
-  -li2c
   -luv
   -std=gnu17
   -std=gnu++17
+
+build_flags =
+  ${portduino_base.build_flags_common}
+  -DHAS_UDP_MULTICAST=1
+  -D_FORTIFY_SOURCE=2
+  -fstack-protector-all -Wstack-protector --param ssp-buffer-size=4
+  -DPORTDUINO_LINUX_HARDWARE
+  -lstdc++fs
+  -lbluetooth
+  -lgpiod
+  -li2c
 lib_ignore =
   Adafruit NeoPixel
   Adafruit ST7735 and ST7789 Library