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>

src/input/InputBroker.cpp

@@ -390,8 +390,11 @@ void InputBroker::Init()
                 seesawRotary = nullptr;
             }
         }
+#ifdef __linux__
+        // Linux evdev keyboard input only — macOS has no <linux/input.h>.
         aLinuxInputImpl = new LinuxInputImpl();
         aLinuxInputImpl->init();
+#endif
     }
 #endif
 #if !MESHTASTIC_EXCLUDE_INPUTBROKER && HAS_TRACKBALL

src/input/LinuxInput.h

@@ -1,5 +1,8 @@
 #pragma once
-#if ARCH_PORTDUINO
+// Linux evdev keyboard input. Only compiled on Linux portduino targets;
+// macOS / non-Linux builds have no <linux/input.h> or epoll, and the
+// headless build doesn't need real keyboards anyway.
+#if ARCH_PORTDUINO && defined(__linux__)
 #include "InputBroker.h"
 #include "concurrency/OSThread.h"
 #include <assert.h>

src/input/LinuxInputImpl.h

@@ -1,4 +1,5 @@
-#ifdef ARCH_PORTDUINO
+// Linux evdev impl. Same Linux-only gating as LinuxInput.h.
+#if defined(ARCH_PORTDUINO) && defined(__linux__)
 #pragma once
 #include "LinuxInput.h"
 #include "main.h"