feat(auth): 登录页改为 ymb 品牌并支持后台配置背景图

lib/pages/auth/auth_form_widgets.dart

@@ -300,7 +300,7 @@ class _AuthBrand extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final copy = _brandCopy(context, centered: !compact);
+    final copy = _brandCopy(centered: !compact);
     if (compact) {
       return Row(
         key: const Key('auth-brand'),
@@ -324,32 +324,14 @@ class _AuthBrand extends StatelessWidget {
     radius: compact ? _compactBrandMarkRadius : _brandMarkRadius,
   );
 
-  Widget _brandCopy(BuildContext context, {required bool centered}) => Column(
-    crossAxisAlignment: centered
-        ? CrossAxisAlignment.center
-        : CrossAxisAlignment.start,
-    children: [
-      Text(
-        AppLocalizations.of(context)!.appName,
-        textAlign: centered ? TextAlign.center : TextAlign.start,
-        style: const TextStyle(
-          color: AppColors.onSurface,
-          fontSize: 24,
-          fontWeight: FontWeight.w700,
-          height: 1.1,
-        ),
-      ),
-      const SizedBox(height: 6),
-      Text(
-        tagline,
-        textAlign: centered ? TextAlign.center : TextAlign.start,
-        style: const TextStyle(
-          color: AppColors.muted,
-          fontSize: 13,
-          height: 1.35,
-        ),
-      ),
-    ],
+  Widget _brandCopy({required bool centered}) => Text(
+    tagline,
+    textAlign: centered ? TextAlign.center : TextAlign.start,
+    style: const TextStyle(
+      color: AppColors.muted,
+      fontSize: 13,
+      height: 1.35,
+    ),
   );
 }
 

lib/pages/auth/auth_view.dart

@@ -7,6 +7,7 @@ import 'package:provider/provider.dart';
 
 import '../../core/data/remote/api_client.dart';
 import '../../core/formatting/error_text.dart';
+import '../../core/data/services/app_config_controller.dart';
 import '../../core/data/services/auth_controller.dart';
 import '../../core/platform/haptics.dart';
 import '../../core/platform/keyboard_inset.dart';
@@ -14,6 +15,7 @@ import '../../core/theme/app_colors.dart';
 import '../../core/theme/app_dimens.dart';
 import '../../core/theme/app_theme.dart';
 import '../../core/widgets/centered_toast.dart';
+import '../../core/widgets/remote_image.dart';
 import '../../core/widgets/subpage_header.dart';
 import '../../l10n/app_localizations.dart';
 import 'auth_legal_links.dart';
@@ -28,7 +30,7 @@ const double _brandMarkSize = 88;
 const double _compactBrandMarkSize = 48;
 const double _brandMarkRadius = 26;
 const double _compactBrandMarkRadius = 14;
-const String _appLogoAsset = 'assets/icon/fruitshorts.png';
+const String _appLogoAsset = 'assets/icon/ymb.png';
 const double _contentMaxWidth = 440;
 const double _fieldHeight = 52;
 const double _fieldRadius = 12;
@@ -276,9 +278,7 @@ class _AuthPageState extends State<AuthPage> {
               ),
             ),
             // 全屏海报背景：压暗保证文字可读，顶部再叠品牌红光。
-            Positioned.fill(
-              child: IgnorePointer(child: _AuthPosterBackdrop()),
-            ),
+            Positioned.fill(child: IgnorePointer(child: _AuthPosterBackdrop())),
             const Positioned.fill(
               child: IgnorePointer(
                 child: DecoratedBox(
@@ -396,80 +396,67 @@ class _AuthPageState extends State<AuthPage> {
     AppLocalizations l10n, {
     required bool compact,
     required double minHeight,
-  }) =>
-      TweenAnimationBuilder<double>(
-        key: const Key('auth-enter-animation'),
-        tween: Tween(begin: 0, end: 1),
-        duration: _enterDuration,
-        curve: Curves.easeOutCubic,
-        builder: (context, value, child) => Opacity(
-          opacity: value,
-          child: Transform.translate(
-            offset: Offset(0, _enterSlideDistance * (1 - value)),
-            child: child,
-          ),
-        ),
-        child: _emailEntryOpen
-            ? Column(
-                crossAxisAlignment: CrossAxisAlignment.stretch,
-                children: [
-                  _AuthBrand(tagline: l10n.authBrandTagline, compact: compact),
-                  SizedBox(height: compact ? _compactBrandGap : 28),
-                  _authCard(l10n),
-                ],
-              )
-            : _landing(l10n, minHeight: minHeight),
-      );
+  }) => TweenAnimationBuilder<double>(
+    key: const Key('auth-enter-animation'),
+    tween: Tween(begin: 0, end: 1),
+    duration: _enterDuration,
+    curve: Curves.easeOutCubic,
+    builder: (context, value, child) => Opacity(
+      opacity: value,
+      child: Transform.translate(
+        offset: Offset(0, _enterSlideDistance * (1 - value)),
+        child: child,
+      ),
+    ),
+    child: _emailEntryOpen
+        ? Column(
+            crossAxisAlignment: CrossAxisAlignment.stretch,
+            children: [
+              _AuthBrand(tagline: l10n.authBrandTagline, compact: compact),
+              SizedBox(height: compact ? _compactBrandGap : 28),
+              _authCard(l10n),
+            ],
+          )
+        : _landing(l10n, minHeight: minHeight),
+  );
 
   /// 落地页内容需要有限高度才能用 Spacer 三段分割，这里显式钉住可用高度。
   Widget _landing(AppLocalizations l10n, {required double minHeight}) =>
       SizedBox(
         height: minHeight,
         child: Column(
-    key: const Key('auth-landing'),
-    crossAxisAlignment: CrossAxisAlignment.stretch,
-    children: [
-      const Spacer(flex: 5),
-      Center(
-        child: _brandMarkWidget(
-          key: const Key('auth-brand-logo'),
-          size: _brandMarkSize,
-          radius: _brandMarkRadius,
+          key: const Key('auth-landing'),
+          crossAxisAlignment: CrossAxisAlignment.stretch,
+          children: [
+            const Spacer(flex: 5),
+            Center(
+              child: _brandMarkWidget(
+                key: const Key('auth-brand-logo'),
+                size: _brandMarkSize,
+                radius: _brandMarkRadius,
+              ),
+            ),
+            const Spacer(flex: 2),
+            _AuthEntryButton(
+              key: const Key('auth-entry-phone'),
+              label: l10n.authPhoneSignIn,
+              icon: Icons.phone_android_rounded,
+              primary: true,
+              onTap: _openPhoneSheet,
+            ),
+            const SizedBox(height: 12),
+            _AuthEntryButton(
+              key: const Key('auth-entry-email'),
+              label: l10n.authEmailSignIn,
+              icon: Icons.mail_outline_rounded,
+              primary: false,
+              onTap: () => setState(() => _emailEntryOpen = true),
+            ),
+            const SizedBox(height: 14),
+            const Opacity(opacity: 0.75, child: AuthLegalLinks()),
+            const Spacer(flex: 6),
+          ],
         ),
-      ),
-      const SizedBox(height: 10),
-      Text(
-        l10n.fruitShortsBrand,
-        textAlign: TextAlign.center,
-        style: const TextStyle(
-          fontFamily: 'Outfit',
-          color: AppColors.onSurface,
-          fontSize: 26,
-          fontWeight: FontWeight.w700,
-          letterSpacing: 2,
-        ),
-      ),
-      const Spacer(flex: 3),
-      _AuthEntryButton(
-        key: const Key('auth-entry-phone'),
-        label: l10n.authPhoneSignIn,
-        icon: Icons.phone_android_rounded,
-        primary: true,
-        onTap: _openPhoneSheet,
-      ),
-      const SizedBox(height: 12),
-      _AuthEntryButton(
-        key: const Key('auth-entry-email'),
-        label: l10n.authEmailSignIn,
-        icon: Icons.mail_outline_rounded,
-        primary: false,
-        onTap: () => setState(() => _emailEntryOpen = true),
-      ),
-      const SizedBox(height: 14),
-      const Opacity(opacity: 0.75, child: AuthLegalLinks()),
-      const Spacer(flex: 6),
-        ],
-      ),
       );
 
   Future<void> _openPhoneSheet() async {
@@ -578,16 +565,26 @@ class _AuthEntryButton extends StatelessWidget {
 }
 
 /// 登录页全屏海报背景（单张，无拼缝）。
+///
+/// 优先用后台下发的 `loginBackgroundUrl`（后台未配置或加载失败时回落到本地默认图）。
 class _AuthPosterBackdrop extends StatelessWidget {
   const _AuthPosterBackdrop();
 
+  static const String _defaultAsset = 'assets/auth/bg_3.jpg';
+
   @override
   Widget build(BuildContext context) {
-    return Image.asset(
+    final remoteUrl = context.watch<AppConfigController>().loginBackgroundUrl;
+    return RemoteImage(
       key: const Key('auth-poster-backdrop'),
-      'assets/auth/bg_3.jpg',
+      remoteUrl,
       fit: BoxFit.cover,
-      alignment: Alignment.center,
+      fallbackWidget: Image.asset(
+        _defaultAsset,
+        key: const Key('auth-poster-default'),
+        fit: BoxFit.cover,
+        alignment: Alignment.center,
+      ),
     );
   }
 }

lib/pages/mine/about_page.dart

@@ -33,7 +33,7 @@ class MineAboutPage extends StatelessWidget {
           ),
           children: [
             Text(
-              l10n.appName,
+              l10n.aboutBrandName,
               textAlign: TextAlign.center,
               style: const TextStyle(
                 fontFamily: 'Outfit',