feat: 文件存储安全加固 + 认证增强 + 媒体URL保护 + provider 重构

## 后端安全加固
- 新增 UserUploadPathResolver: 用户上传文件路径安全解析, 防目录穿越
- LocalReportFileStorage: 文件存储路径安全加固
- local_account_file_cleanup: 账号删除时文件清理逻辑增强
- AuthService: 认证逻辑增强
- file_endpoints / report_endpoints: 文件访问接口安全加固
- ai_chat_endpoints / doctor_endpoints: 接口安全调整
- Program.cs: 服务注册调整

## 前端认证与媒体
- 新增 authenticated_network_image.dart: 带认证的图片加载组件
- auth_provider: 认证状态管理大幅增强(+173)
- api_client: 网络客户端增强(+124)
- chat_provider: 聊天 provider 重构(+76)
- omron_device_provider: 蓝牙设备 provider 增强(+53)
- sse_handler: SSE 处理增强(+35)
- consultation_provider / data_providers / conversation_history_provider: 调整

## 页面调整
- remaining_pages: 健康档案/饮食记录等页面增强(+115)
- home_page / chat_messages_view: 主页微调
- doctor 端多页微调(consultations/dashboard/followups/patient_detail/profile/report_detail/reports)
- report_pages / settings_pages / notification_prefs_page: 微调
- device_scan_page / diet_capture_page / admin_home_page: 微调

## 测试
- 新增 file_path_security_tests: 文件路径安全测试
- 新增 protected_media_url_test: 媒体URL保护测试
- 新增 user_session_identity_test: 用户会话身份测试
- account_deletion_tests / application_service_tests / auth_tests: 更新

backend/src/Health.Infrastructure/Users/local_account_file_cleanup.cs

@@ -9,14 +9,23 @@ public sealed class LocalAccountFileCleanup(string uploadsRoot) : IAccountFileCl
 
     public Task DeleteAsync(Guid userId, AccountFileReferences references, CancellationToken ct)
     {
-        var fileUrls = new HashSet<string>(references.FileUrls, StringComparer.OrdinalIgnoreCase);
-        foreach (var metadataJson in references.ConversationMetadataJson)
-            AddMetadataUrls(fileUrls, metadataJson);
-
-        foreach (var fileUrl in fileUrls)
+        // 正式报告路径来自服务端生成的报告记录，只允许删除 reports 目录中的文件。
+        foreach (var fileUrl in references.FileUrls)
         {
             ct.ThrowIfCancellationRequested();
-            var localPath = ResolveLocalPath(fileUrl);
+            var localPath = ResolveReportPath(fileUrl);
+            if (localPath != null && File.Exists(localPath)) File.Delete(localPath);
+        }
+
+        // 对话元数据可能包含客户端传入的 URL，只允许解析当前账号自己的目录。
+        var attachmentUrls = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+        foreach (var metadataJson in references.ConversationMetadataJson)
+            AddMetadataUrls(attachmentUrls, metadataJson);
+
+        foreach (var fileUrl in attachmentUrls)
+        {
+            ct.ThrowIfCancellationRequested();
+            var localPath = ResolveOwnedAttachmentPath(userId, fileUrl);
             if (localPath != null && File.Exists(localPath)) File.Delete(localPath);
         }
 
@@ -52,31 +61,65 @@ public sealed class LocalAccountFileCleanup(string uploadsRoot) : IAccountFileCl
         if (!string.IsNullOrWhiteSpace(value)) fileUrls.Add(value);
     }
 
-    private string? ResolveLocalPath(string fileUrl)
+    private string? ResolveReportPath(string fileUrl)
     {
-        var urlPath = fileUrl;
-        if (Uri.TryCreate(fileUrl, UriKind.Absolute, out var absoluteUri))
-            urlPath = absoluteUri.AbsolutePath;
-
-        var uploadsIndex = urlPath.IndexOf("/uploads/", StringComparison.OrdinalIgnoreCase);
-        if (uploadsIndex < 0) return null;
-
-        string relativePath;
         try
         {
-            relativePath = Uri.UnescapeDataString(urlPath[(uploadsIndex + "/uploads/".Length)..]);
+            var path = Uri.TryCreate(fileUrl, UriKind.Absolute, out var absolute)
+                ? absolute.AbsolutePath
+                : fileUrl.Split('?', 2)[0];
+            var prefixIndex = path.IndexOf("/uploads/reports/", StringComparison.OrdinalIgnoreCase);
+            if (prefixIndex < 0) return null;
+            var fileName = Uri.UnescapeDataString(path[(prefixIndex + "/uploads/reports/".Length)..]);
+            return ResolveInside(Path.Combine(_uploadsRoot, "reports"), fileName);
+        }
+        catch (ArgumentException)
+        {
+            return null;
         }
         catch (UriFormatException)
         {
             return null;
         }
+    }
 
-        var queryIndex = relativePath.IndexOfAny(['?', '#']);
-        if (queryIndex >= 0) relativePath = relativePath[..queryIndex];
-        relativePath = relativePath.Replace('/', Path.DirectorySeparatorChar);
+    private string? ResolveOwnedAttachmentPath(Guid userId, string fileUrl)
+    {
+        try
+        {
+            var path = Uri.TryCreate(fileUrl, UriKind.Absolute, out var absolute)
+                ? absolute.AbsolutePath
+                : fileUrl.Split('?', 2)[0];
+            path = Uri.UnescapeDataString(path);
+            var protectedPrefix = "/api/files/content/";
+            var protectedIndex = path.IndexOf(protectedPrefix, StringComparison.OrdinalIgnoreCase);
+            var legacyPrefix = $"/uploads/users/{userId:N}/";
+            var legacyIndex = path.IndexOf(legacyPrefix, StringComparison.OrdinalIgnoreCase);
+            var fileName = protectedIndex >= 0
+                ? path[(protectedIndex + protectedPrefix.Length)..]
+                : legacyIndex >= 0
+                    ? path[(legacyIndex + legacyPrefix.Length)..]
+                    : null;
+            return fileName == null
+                ? null
+                : ResolveInside(Path.Combine(_uploadsRoot, "users", userId.ToString("N")), fileName);
+        }
+        catch (ArgumentException)
+        {
+            return null;
+        }
+        catch (UriFormatException)
+        {
+            return null;
+        }
+    }
 
-        var fullPath = Path.GetFullPath(Path.Combine(_uploadsRoot, relativePath));
-        var rootPrefix = _uploadsRoot.TrimEnd(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar)
+    private static string? ResolveInside(string root, string fileName)
+    {
+        if (string.IsNullOrWhiteSpace(fileName) || fileName != Path.GetFileName(fileName)) return null;
+        var fullRoot = Path.GetFullPath(root);
+        var fullPath = Path.GetFullPath(Path.Combine(fullRoot, fileName));
+        var rootPrefix = fullRoot.TrimEnd(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar)
             + Path.DirectorySeparatorChar;
         return fullPath.StartsWith(rootPrefix, StringComparison.OrdinalIgnoreCase) ? fullPath : null;
     }