feat: UI 系统中心化 + 趋势图重构 + 法律文档 H5 上线

- UI 系统: 新增 design_tokens / module_visuals / app_buttons / app_status_badge / app_toast / ai_content 六个共享模块; 28 个页面接入, SnackBar 全部替换为 AppToast
- 趋势图: 直线折线 + 渐变填充 + 阴影; 去网格线; X 轴日+月份分隔; Y 轴整数刻度最多 4 个; 点击数据点/录入记录显示上方浮层, 选中点变实心
- 法律文档 H5: 后端 wwwroot 托管隐私政策/服务协议/关于/个人信息收集清单/第三方 SDK 清单 + 索引页; Program.cs 启用 UseDefaultFiles + UseStaticFiles
- 其他: auth_provider 登录流程调整; api_client IP 适配; 主页智能体栏间距优化

health_app/lib/pages/diet/diet_capture_page.dart

@@ -5,9 +5,11 @@ import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../../core/navigation_provider.dart';
 import '../../core/app_colors.dart';
+import '../../core/app_module_visuals.dart';
 import '../../core/app_theme.dart';
 import '../../providers/auth_provider.dart';
 import '../../utils/sse_handler.dart';
+import '../../widgets/app_toast.dart';
 
 final dietProvider = NotifierProvider<DietNotifier, DietState>(
   DietNotifier.new,
@@ -303,14 +305,11 @@ class DietNotifier extends Notifier<DietState> {
 }
 
 // ─────────── 饮食主题色（暖橙系，不再用紫色）───────────
-const _dietAccent = Color(0xFFF97316);
-const _dietAccentLight = Color(0xFFFFF3E0);
+const _dietVisual = AppModuleVisuals.diet;
+const _dietAccent = AppColors.diet;
+const _dietAccentLight = AppColors.dietLight;
 const _dietKcalText = Color(0xFF9A3412);
-const _dietGradient = LinearGradient(
-  begin: Alignment.topLeft,
-  end: Alignment.bottomRight,
-  colors: [Color(0xFFF6D365), Color(0xFFFDA085)],
-);
+const _dietGradient = AppColors.dietGradient;
 
 class DietCapturePage extends ConsumerStatefulWidget {
   const DietCapturePage({super.key});
@@ -362,47 +361,47 @@ class _DietCapturePageState extends ConsumerState<DietCapturePage> {
 
     return SingleChildScrollView(
       padding: const EdgeInsets.fromLTRB(16, 12, 16, 24),
-        child: Column(
-          children: [
-            // 图片自适应显示
-            Container(
-              padding: const EdgeInsets.all(8),
-              decoration: BoxDecoration(
-                color: Colors.white,
-                borderRadius: BorderRadius.circular(24),
-                border: Border.all(color: AppColors.borderLight),
-                boxShadow: AppColors.cardShadowLight,
-              ),
-              child: ClipRRect(
-                borderRadius: BorderRadius.circular(18),
-                child: Image.file(
-                  File(state.imagePath!),
-                  width: screenW - 48,
-                  height: 220,
-                  fit: BoxFit.cover,
-                ),
+      child: Column(
+        children: [
+          // 图片自适应显示
+          Container(
+            padding: const EdgeInsets.all(8),
+            decoration: BoxDecoration(
+              color: Colors.white,
+              borderRadius: BorderRadius.circular(24),
+              border: Border.all(color: AppColors.borderLight),
+              boxShadow: AppColors.cardShadowLight,
+            ),
+            child: ClipRRect(
+              borderRadius: BorderRadius.circular(18),
+              child: Image.file(
+                File(state.imagePath!),
+                width: screenW - 48,
+                height: 220,
+                fit: BoxFit.cover,
               ),
             ),
+          ),
+          const SizedBox(height: 16),
+          _buildMealSelector(ref),
+          const SizedBox(height: 16),
+          if (state.isAnalyzing)
+            _buildAnalyzing(state)
+          else if (state.foods.isEmpty)
+            _buildNoFoodHint()
+          else ...[
+            _buildFoodList(ref),
             const SizedBox(height: 16),
-            _buildMealSelector(ref),
-            const SizedBox(height: 16),
-            if (state.isAnalyzing)
-              _buildAnalyzing(state)
-            else if (state.foods.isEmpty)
-              _buildNoFoodHint()
-            else ...[
-              _buildFoodList(ref),
+            _buildNutritionCard(ref),
+            if (state.commentary != null && state.commentary!.isNotEmpty) ...[
               const SizedBox(height: 16),
-              _buildNutritionCard(ref),
-              if (state.commentary != null && state.commentary!.isNotEmpty) ...[
-                const SizedBox(height: 16),
-                _buildAiCommentary(state.commentary!),
-              ],
-              const SizedBox(height: 20),
-              _buildSaveButton(),
+              _buildAiCommentary(state.commentary!),
             ],
+            const SizedBox(height: 20),
+            _buildSaveButton(),
           ],
-        ),
+        ],
+      ),
     );
   }
 
@@ -931,11 +930,7 @@ class _DietCapturePageState extends ConsumerState<DietCapturePage> {
                   color: _dietAccentLight,
                   borderRadius: BorderRadius.circular(10),
                 ),
-                child: const Icon(
-                  Icons.auto_awesome,
-                  size: 20,
-                  color: _dietAccent,
-                ),
+                child: Icon(_dietVisual.icon, size: 20, color: _dietAccent),
               ),
               const SizedBox(width: 12),
               Expanded(
@@ -981,6 +976,13 @@ class _DietCapturePageState extends ConsumerState<DietCapturePage> {
               if (mounted) popRoute(ref);
             } catch (e) {
               debugPrint('[Diet] 保存记录失败: $e');
+              if (mounted) {
+                AppToast.show(
+                  context,
+                  '保存失败，请检查网络后重试',
+                  type: AppToastType.error,
+                );
+              }
             }
           },
           child: const Row(