feat(flutter): 应用浅色暖橙视觉主题

lib/core/widgets/app_bottom_nav.dart

@@ -7,7 +7,7 @@ import 'package:flutter/material.dart';
 import '../theme/app_colors.dart';
 import '../theme/app_dimens.dart';
 
-/// One destination rendered by [AppBottomNav].
+/// 底部导航普通目的地。
 class AppBottomNavItem {
   const AppBottomNavItem({
     required this.tabKey,
@@ -26,41 +26,69 @@ class AppBottomNavItem {
   final bool selected;
 }
 
-/// Shared bottom navigation used by the root shell and standalone tabs.
+/// 底部导航中央操作按钮。
+class AppBottomNavCenterAction {
+  const AppBottomNavCenterAction({
+    required this.label,
+    required this.onTap,
+    this.key = const Key('nav-center-action'),
+  });
+
+  final Key key;
+  final String label;
+  final VoidCallback onTap;
+}
+
+/// 全局五槽底部导航。
 class AppBottomNav extends StatelessWidget {
   const AppBottomNav({
     super.key,
     required this.items,
+    this.centerAction,
     this.backgroundColor = AppColors.bar,
     this.barKey,
   });
 
   final List<AppBottomNavItem> items;
+  final AppBottomNavCenterAction? centerAction;
   final Color backgroundColor;
   final Key? barKey;
 
   @override
-  Widget build(BuildContext context) => ClipRect(
-    child: BackdropFilter(
-      filter: ImageFilter.blur(sigmaX: 20, sigmaY: 20),
-      child: SafeArea(
-        top: false,
-        child: Container(
-          key: barKey,
-          height: AppDimens.navHeight,
-          decoration: BoxDecoration(
-            color: backgroundColor.withValues(alpha: 0.95),
-            border: const Border(
-              top: BorderSide(color: AppColors.outlineVariantDark),
+  Widget build(BuildContext context) {
+    final action = centerAction;
+    return ClipRect(
+      child: BackdropFilter(
+        filter: ImageFilter.blur(sigmaX: 20, sigmaY: 20),
+        child: SafeArea(
+          top: false,
+          child: Container(
+            key: barKey,
+            height: AppDimens.navHeight,
+            decoration: BoxDecoration(
+              color: backgroundColor.withValues(alpha: 0.95),
+              border: const Border(top: BorderSide(color: AppColors.border)),
             ),
-          ),
-          child: Row(
-            children: [for (final item in items) _NavDestination(item: item)],
+            child: action == null
+                ? Row(
+                    children: [
+                      for (final item in items) _NavDestination(item: item),
+                    ],
+                  )
+                : Row(
+                    children: [
+                      for (final item in items.take(2))
+                        _NavDestination(item: item),
+                      Expanded(child: _CenterDestination(action: action)),
+                      for (final item in items.skip(2))
+                        _NavDestination(item: item),
+                    ],
+                  ),
           ),
         ),
       ),
-    ),
-  );
+    );
+  }
 }
 
 class _NavDestination extends StatelessWidget {
@@ -78,7 +106,7 @@ class _NavDestination extends StatelessWidget {
         key: item.tabKey,
         onTap: item.onTap,
         child: ConstrainedBox(
-          constraints: const BoxConstraints(minHeight: 48),
+          constraints: const BoxConstraints(minHeight: AppDimens.navHeight),
           child: Column(
             mainAxisAlignment: MainAxisAlignment.center,
             children: [
@@ -91,7 +119,7 @@ class _NavDestination extends StatelessWidget {
                   size: AppDimens.navIcon,
                   color: item.selected
                       ? AppColors.blue
-                      : Colors.white.withValues(alpha: 0.45),
+                      : AppColors.navUnselected,
                 ),
               ),
               const SizedBox(height: 2),
@@ -104,7 +132,7 @@ class _NavDestination extends StatelessWidget {
                   fontWeight: item.selected ? FontWeight.w700 : FontWeight.w500,
                   color: item.selected
                       ? AppColors.blue
-                      : Colors.white.withValues(alpha: 0.45),
+                      : AppColors.navUnselected,
                   letterSpacing: 0,
                 ),
               ),
@@ -115,3 +143,53 @@ class _NavDestination extends StatelessWidget {
     ),
   );
 }
+
+class _CenterDestination extends StatelessWidget {
+  const _CenterDestination({required this.action});
+
+  final AppBottomNavCenterAction action;
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Semantics(
+        button: true,
+        label: action.label,
+        child: Material(
+          color: Colors.transparent,
+          shape: const CircleBorder(),
+          clipBehavior: Clip.antiAlias,
+          child: Ink(
+            width: AppDimens.navCenter,
+            height: AppDimens.navCenter,
+            decoration: const BoxDecoration(
+              shape: BoxShape.circle,
+              gradient: LinearGradient(
+                begin: Alignment.topLeft,
+                end: Alignment.bottomRight,
+                colors: [AppColors.navCenterStart, AppColors.navCenterEnd],
+              ),
+              boxShadow: [
+                BoxShadow(
+                  color: AppColors.navCenterShadow,
+                  blurRadius: 14,
+                  offset: Offset(0, 5),
+                ),
+              ],
+            ),
+            child: InkWell(
+              key: action.key,
+              customBorder: const CircleBorder(),
+              onTap: action.onTap,
+              child: const Icon(
+                Icons.add_rounded,
+                color: AppColors.onPrimary,
+                size: AppDimens.navCenterIcon,
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}

lib/core/widgets/glass_panel.dart

@@ -7,7 +7,7 @@ import 'package:flutter/material.dart';
 import '../theme/app_colors.dart';
 import '../theme/app_dimens.dart';
 
-/// Dark glass surface used by the home info card and floating controls.
+/// 首页信息卡与浮层控件使用的浅色玻璃面板。
 class GlassPanel extends StatelessWidget {
   const GlassPanel({
     super.key,
@@ -38,7 +38,7 @@ class GlassPanel extends StatelessWidget {
             const LinearGradient(
               begin: Alignment.topLeft,
               end: Alignment.bottomRight,
-              colors: [Color(0x24FFFFFF), Color(0x0DFFFFFF)],
+              colors: [Color(0xE6FFFFFF), Color(0xB3FFFDFB)],
             ),
       ),
       child: Padding(padding: padding ?? EdgeInsets.zero, child: child),