feat: AI 意图路由/草稿存储 + Prompts 模块化 + UI 视觉统一 + AI 同意门 + 资源更新

后端:
- 新增 ai_intent_router 意图路由
- 新增 AiEntryDraft 草稿存储 + EF 迁移
- 新增 Prompts 模块化（global/modules/rag/router）
- AI Agent handlers 扩展

前端:
- 新增 AI 同意门 (ai_consent_gate/provider/details_page)
- HealthMetricVisuals 视觉统一
- 设备扫描/管理页面优化
- agent 插图替换 + 趋势指标图标

配置:
- DeepSeek 模型改 deepseek-v4-flash
- .gitignore 加 artifacts/audit
- build.gradle.kts 签名配置调整

backend/src/Health.Application/Users/UserContracts.cs

@@ -14,7 +14,8 @@ public sealed record UserProfileDto(
 public sealed record UserProfileUpdateRequest(
     string? Name,
     string? Gender,
-    DateOnly? BirthDate);
+    DateOnly? BirthDate,
+    string? AvatarUrl);
 
 public sealed record AccountFileReferences(
     IReadOnlyList<string> FileUrls,

backend/src/Health.Application/Users/UserService.cs

@@ -28,6 +28,7 @@ public sealed class UserService(
         if (request.Name != null) user.Name = request.Name;
         if (request.Gender != null) user.Gender = request.Gender;
         if (request.BirthDate.HasValue) user.BirthDate = request.BirthDate.Value;
+        if (request.AvatarUrl != null) user.AvatarUrl = request.AvatarUrl;
         user.UpdatedAt = DateTime.UtcNow;
         await _users.SaveChangesAsync(ct);
         return true;