chore(app): launcher icons, native splash, and web platform

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.

apps/app_seeds/pubspec.yaml

@@ -50,6 +50,7 @@ dependencies:
   cupertino_icons: ^1.0.8
   material_symbols_icons: ^4.2951.0
   url_launcher: ^6.3.2
+  package_info_plus: ^9.0.1
 
 dev_dependencies:
   flutter_test:
@@ -62,6 +63,34 @@ dev_dependencies:
   drift_dev: ^2.28.0
   slang_build_runner: ^4.7.0
   mocktail: ^1.0.4
+  flutter_launcher_icons: ^0.14.4
+  flutter_native_splash: ^2.4.7
+
+# App launcher icon (green sprout on the light-green canvas). Regenerate with:
+#   dart run flutter_launcher_icons
+flutter_launcher_icons:
+  image_path: assets/icon.png
+  android: true
+  ios: true
+  remove_alpha_ios: true
+  adaptive_icon_background: "#E7F1E0"
+  adaptive_icon_foreground: assets/icon_foreground.png
+  web:
+    generate: true
+    image_path: assets/icon.png
+    background_color: "#E7F1E0"
+    theme_color: "#2F7D34"
+
+# Native splash: the sprout on the canvas colour, light & dark. Regenerate with:
+#   dart run flutter_native_splash:create
+flutter_native_splash:
+  color: "#E7F1E0"
+  color_dark: "#22521E"
+  image: assets/splash_logo.png
+  android_12:
+    image: assets/splash_logo.png
+    color: "#E7F1E0"
+    color_dark: "#22521E"
 
 flutter:
   uses-material-design: true