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/app_drawer.dart

@@ -38,7 +38,14 @@ class AppDrawer extends StatelessWidget {
             _SoonItem(icon: Icons.group_outlined, label: t.menu.following),
             const Spacer(),
             const Divider(),
-            _SoonItem(icon: Icons.settings_outlined, label: t.menu.settings),
+            _ActiveItem(
+              icon: const Icon(Icons.settings_outlined),
+              label: t.menu.settings,
+              onTap: () {
+                Navigator.of(context).pop();
+                context.go('/settings');
+              },
+            ),
           ],
         ),
       ),

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(

apps/app_seeds/lib/ui/settings_screen.dart

@@ -0,0 +1,86 @@
+import 'package:flutter/material.dart';
+
+import '../i18n/strings.g.dart';
+import 'theme.dart';
+
+/// Basic settings: app language and an "about" section.
+class SettingsScreen extends StatelessWidget {
+  const SettingsScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final t = context.t;
+    final current = TranslationProvider.of(context).flutterLocale.languageCode;
+    return Scaffold(
+      appBar: AppBar(title: Text(t.menu.settings)),
+      body: ListView(
+        children: [
+          _SectionHeader(t.settings.language),
+          _LanguageTile(
+            label: t.settings.langEs,
+            selected: current == 'es',
+            onTap: () => LocaleSettings.setLocale(AppLocale.es),
+          ),
+          _LanguageTile(
+            label: t.settings.langEn,
+            selected: current == 'en',
+            onTap: () => LocaleSettings.setLocale(AppLocale.en),
+          ),
+          ListTile(
+            leading: const Icon(Icons.smartphone_outlined),
+            title: Text(t.settings.systemLanguage),
+            onTap: () => LocaleSettings.useDeviceLocale(),
+          ),
+          const Divider(),
+          _SectionHeader(t.settings.about),
+          ListTile(
+            leading: Image.asset('assets/logo.png', width: 32),
+            title: Text(t.app.title),
+            subtitle: Text(t.settings.aboutText),
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+class _SectionHeader extends StatelessWidget {
+  const _SectionHeader(this.text);
+
+  final String text;
+
+  @override
+  Widget build(BuildContext context) {
+    return Padding(
+      padding: const EdgeInsets.fromLTRB(16, 16, 16, 4),
+      child: Text(
+        text,
+        style: Theme.of(context).textTheme.titleSmall?.copyWith(
+          color: seedGreenDark,
+          fontWeight: FontWeight.w600,
+        ),
+      ),
+    );
+  }
+}
+
+class _LanguageTile extends StatelessWidget {
+  const _LanguageTile({
+    required this.label,
+    required this.selected,
+    required this.onTap,
+  });
+
+  final String label;
+  final bool selected;
+  final VoidCallback onTap;
+
+  @override
+  Widget build(BuildContext context) {
+    return ListTile(
+      title: Text(label),
+      trailing: selected ? const Icon(Icons.check, color: seedGreen) : null,
+      onTap: onTap,
+    );
+  }
+}