Adopt the shared icon family (python_pkg/app_icons in testsAndMisc): a
charcoal #1B1D21 field carrying a deep-purple checklist glyph, deep purple
being this app's own theme seedColor. Two ticked-off rows rather than a lone
checkmark, so it reads as a notes app and not as a generic "done" badge.
Android gains the adaptive-icon layers the project never had, including an
Android 13 monochrome layer.
Linux needs separate handling: Flutter's GTK runner never sets a window icon,
so my_application.cc now calls gtk_window_set_icon_name and
install_desktop_entry.sh populates the hicolor theme from the pre-rendered
PNGs in linux/icons (committed, so the installer needs no image tooling).
StartupWMClass is the APPLICATION_ID rather than the binary name - verified
with xprop against a running window, where WM_CLASS is the GApplication id.
No Dart code changes, so test coverage is unaffected.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
