feat: initialize Flutter project with version management

- Initialize Flutter 3.38 project with all platforms
- Add build-time version generation from pubspec.yaml
- Print version to console on app startup
- Create CHANGELOG.md following Keep a Changelog format
- Update .gitignore for Flutter + generated files
- Basic app scaffold with Material 3 theming

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

linux/runner/main.cc

@@ -0,0 +1,6 @@
+#include "my_application.h"
+
+int main(int argc, char** argv) {
+  g_autoptr(MyApplication) app = my_application_new();
+  return g_application_run(G_APPLICATION(app), argc, argv);
+}