Fix CI coverage: remove ASan conflict, fix lcov directory, add coverage flush

- Remove -fsanitize=address from coverage build (conflicts with --coverage)
- Fix lcov directory from .pio/build/coverage/src to .pio/build/coverage
- Add --ignore-errors empty to handle empty coverage gracefully
- Add flushCoverageAndExit() utility for proper coverage data flush

Author: MATBckh22

.github/workflows/test_native.yml

@@ -7,7 +7,7 @@ on:
 permissions: {}
 
 env:
-  LCOV_CAPTURE_FLAGS: --quiet --capture --include "${PWD}/src/*" --exclude '*/src/mesh/generated/*' --directory .pio/build/coverage/src --base-directory "${PWD}"
+  LCOV_CAPTURE_FLAGS: --quiet --capture --include "${PWD}/src/*" --exclude '*/src/mesh/generated/*' --directory .pio/build/coverage --base-directory "${PWD}" --ignore-errors empty
 
 jobs:
   simulator-tests:

src/platform/portduino/PortduinoGlue.h

@@ -470,4 +470,14 @@ extern struct portduino_config_struct {
         out << YAML::EndMap; // General
         return out.c_str();
     }
-} portduino_config;
+} portduino_config;
+
+// Utility function to flush coverage data before exit
+inline void flushCoverageAndExit(int code) {
+#ifdef __GNUC__
+    // Flush coverage data when built with --coverage
+    extern "C" void __gcov_flush(void);
+    __gcov_flush();
+#endif
+    exit(code);
+}

variants/native/portduino/platformio.ini

@@ -125,4 +125,4 @@ build_src_filter = ${env:native-tft.build_src_filter}
 
 [env:coverage]
 extends = env:native
-build_flags = -lgcov --coverage -fprofile-abs-path -fsanitize=address ${env:native.build_flags}
+build_flags = -lgcov --coverage -fprofile-abs-path ${env:native.build_flags}