feat: 新增永久删除文件接口和前端删除按钮

后端新增 POST api/files/delete 接口，同时删除物理文件、缩略图和数据库记录。
前端在 FileCard 和 FileListItem 中增加 hover 可见的删除按钮，点击后弹出确认提示。

FileShare-Services/Endpoints/AppEndpoints.cs

@@ -82,6 +82,10 @@ namespace FileShare_Services.Endpoints
                     .WithOpenApi("FileLibrary", "保存文件播放进度。")
                     .WithName("SaveFileProgress");
 
+                endpoints.MapPost<IFileLibraryEndpointService, DeleteFileRequest>("api/files/delete", (service, request, _) => service.DeleteFileAsync(request))
+                    .WithOpenApi("FileLibrary", "永久删除文件（物理文件+数据库记录）。")
+                    .WithName("DeleteFile");
+
                 endpoints.MapGet<IFileLibraryEndpointService, FileQueryRequest>("api/files/detail", (service, request, _) => service.GetFileAsync(request))
                     .WithOpenApi("FileLibrary", "查询文件详情。")
                     .WithName("GetFileDetail");

FileShare-Services/Services/FileLibrary/FileLibraryContracts.cs

@@ -34,6 +34,12 @@ namespace FileShare_Services.Services.FileLibrary
     public sealed record DeleteLibraryRootRequest(
         [property: JsonPropertyName("id")] int Id);
 
+    /// <summary>
+    /// 永久删除文件的请求。
+    /// </summary>
+    public sealed record DeleteFileRequest(
+        [property: JsonPropertyName("id")] int Id);
+
     /// <summary>
     /// 查询服务器子目录的请求。
     /// </summary>

FileShare-Services/Services/FileLibrary/FileLibraryEndpointService.cs

@@ -113,6 +113,14 @@ namespace FileShare_Services.Services.FileLibrary
             return ResponseHelper.Succeed();
         }
 
+        /// <inheritdoc />
+        public async Task<IApiResponse> DeleteFileAsync(DeleteFileRequest request)
+        {
+            ValidateFileId(request.Id);
+            await fileLibrary.DeleteFileAsync(request.Id);
+            return ResponseHelper.Succeed("文件已永久删除。");
+        }
+
         /// <summary>
         /// 验证文件 ID 是否有效，无效时抛出 <see cref="ArgumentException"/>。
         /// </summary>

FileShare-Services/Services/FileLibrary/FileLibraryService.cs

@@ -545,6 +545,54 @@ namespace FileShare_Services.Services.FileLibrary
             }
         }
 
+        /// <inheritdoc />
+        public async Task DeleteFileAsync(int id, CancellationToken cancellationToken = default)
+        {
+            var record = await db.ManagedFileRecords
+                .Include(f => f.Thumbnail)
+                .FirstOrDefaultAsync(f => f.Id == id, cancellationToken);
+
+            if (record is null)
+            {
+                return;
+            }
+
+            // 删除物理文件
+            try
+            {
+                if (File.Exists(record.AbsolutePath))
+                {
+                    File.Delete(record.AbsolutePath);
+                }
+            }
+            catch (Exception ex)
+            {
+                Serilog.Log.Warning(ex, "删除物理文件失败 FilePath={FilePath}", record.AbsolutePath);
+            }
+
+            // 删除缩略图文件
+            if (record.Thumbnail is not null)
+            {
+                try
+                {
+                    var thumbnailPath = thumbnailService.GetAbsolutePath(record.Thumbnail.RelativePath);
+                    if (File.Exists(thumbnailPath))
+                    {
+                        File.Delete(thumbnailPath);
+                    }
+                }
+                catch (Exception ex)
+                {
+                    Serilog.Log.Warning(ex, "删除缩略图文件失败 ThumbnailId={ThumbnailId}", record.ThumbnailId);
+                }
+
+                db.ManagedThumbnailMaps.Remove(record.Thumbnail);
+            }
+
+            db.ManagedFileRecords.Remove(record);
+            await db.SaveChangesAsync(cancellationToken);
+        }
+
         /// <summary>
         /// 深度优先遍历目录树，枚举所有被 <see cref="MediaFileTypes"/> 支持的媒体文件路径。
         /// 遇到无权限的目录时跳过该分支继续遍历。

FileShare-Services/Services/FileLibrary/IFileLibraryEndpointService.cs

@@ -105,5 +105,12 @@ namespace FileShare_Services.Services.FileLibrary
         /// <param name="request">包含文件 ID 和播放位置的请求。</param>
         /// <returns>API 响应。</returns>
         Task<IApiResponse> SaveFileProgressAsync(SaveFileProgressRequest request);
+
+        /// <summary>
+        /// 永久删除指定文件。
+        /// </summary>
+        /// <param name="request">包含文件 ID 的请求。</param>
+        /// <returns>API 响应。</returns>
+        Task<IApiResponse> DeleteFileAsync(DeleteFileRequest request);
     }
 }

FileShare-Services/Services/FileLibrary/IFileLibraryService.cs

@@ -121,5 +121,12 @@ namespace FileShare_Services.Services.FileLibrary
         /// <param name="position">播放位置（秒）。</param>
         /// <param name="cancellationToken">取消令牌。</param>
         Task SaveFileProgressAsync(int id, double position, CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// 永久删除指定文件，同时删除物理文件和缩略图。
+        /// </summary>
+        /// <param name="id">文件记录 ID。</param>
+        /// <param name="cancellationToken">取消令牌。</param>
+        Task DeleteFileAsync(int id, CancellationToken cancellationToken = default);
     }
 }