feat(shell): real sprout logo on home + basic Settings screen

- Bundle the real sprout logo (docs/logo.png → assets/logo.png) and show it on
  the home menu instead of a Material icon.
- Settings screen: switch language (Español / English / system) via slang, plus
  an About tile (logo, app name, one-line description). Drawer "Settings" is now
  active and routes to /settings.

Tests: drawer Settings opens the screen and shows the language options. 54 green.

apps/app_seeds/lib/ui/home_screen.dart

@@ -1,6 +1,5 @@
 import 'package:flutter/material.dart';
 import 'package:go_router/go_router.dart';
-import 'package:material_symbols_icons/symbols.dart';
 
 import '../i18n/strings.g.dart';
 import 'app_drawer.dart';
@@ -31,11 +30,10 @@ class HomeScreen extends StatelessWidget {
                   mainAxisSize: MainAxisSize.min,
                   crossAxisAlignment: CrossAxisAlignment.stretch,
                   children: [
-                    const Icon(
-                      Symbols.eco,
-                      size: 120,
-                      color: seedGreen,
-                      fill: 1,
+                    Image.asset(
+                      'assets/logo.png',
+                      height: 140,
+                      fit: BoxFit.contain,
                     ),
                     const SizedBox(height: 40),
                     _MenuButton(