Add an "About" entry to the navigation drawer (below Settings) so the
About screen is reachable without opening Settings first.
Recolour the launcher icon and native splash to a white sprout on brand
green (#2F7D34) — the previous dark-green-on-light-green had almost no
contrast. Regenerate Android, iOS and web icons and the light/dark splash.
Add flutter_launcher_icons + flutter_native_splash config (green sprout
on the #E7F1E0 canvas, light & dark) and regenerate Android/iOS assets.
Enable the web platform (favicon, manifest, PWA icons). Add
package_info_plus for the version string shown on the About screen.
