Release 1.0.0: rename to NoMines, add leaderboard, theme support and release metadata

- Rename app/binary/app-id to nomines (io.github.bemagri.nomines), config dir
  moves to ~/.config/nomines with legacy path fallback
- Add persistent best-time leaderboard (Glib::KeyFile)
- Theme-aware board following system light/dark preference
- Beveled 3D cells, confetti win animation, keyboard shortcuts,
  right-click chording, per-difficulty window sizing
- Add AppStream metainfo, validate desktop file and metainfo via meson tests
- Fix license metadata to GPL-3.0-or-later and real homepage

src/main.cpp

@@ -2,7 +2,7 @@
 #include <gtkmm/application.h>
 
 int main(int argc, char* argv[]) {
-    auto app = Gtk::Application::create("org.gtkmm.minesweeper");
+    auto app = Gtk::Application::create("io.github.bemagri.nomines");
     
     return app->make_window_and_run<MainWindow>(argc, argv);
 }