feat: 文件搜索、视频续播与目录文件过滤

- 前端 Header 新增搜索栏，接入已有 SearchFiles API，结果支持列表/网格视图
- 新增 PlaybackPosition 数据库列与 /api/files/progress 端点，播放进度存服务端
- 播放中每 5 秒自动保存进度，再次打开视频时弹出"继续播放"提示
- 目录浏览新增媒体类型过滤条（全部/视频/音频/文本），前端即时过滤
- 新增 4 种数据库迁移（AddPlaybackPosition）

FileShare-Services/Endpoints/AppEndpoints.cs

@@ -77,6 +77,10 @@ namespace FileShare_Services.Endpoints
                     .WithOpenApi("FileLibrary", "标记文件已播放。")
                     .WithName("MarkFilePlayed");
 
+                endpoints.MapPost<IFileLibraryEndpointService, SaveFileProgressRequest>("api/files/progress", (service, request, _) => service.SaveFileProgressAsync(request))
+                    .WithOpenApi("FileLibrary", "保存文件播放进度。")
+                    .WithName("SaveFileProgress");
+
                 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

@@ -59,6 +59,13 @@ namespace FileShare_Services.Services.FileLibrary
     public sealed record MarkFilePlayedRequest(
         [property: JsonPropertyName("id")] int Id);
 
+    /// <summary>
+    /// 保存文件播放进度的请求。
+    /// </summary>
+    public sealed record SaveFileProgressRequest(
+        [property: JsonPropertyName("id")] int Id,
+        [property: JsonPropertyName("position")] double Position);
+
     /// <summary>
     /// 分页搜索已扫描文件的请求。
     /// </summary>
@@ -121,7 +128,8 @@ namespace FileShare_Services.Services.FileLibrary
         bool BrowserPlayable,
         string? ThumbnailUrl = null,
         double? VideoDuration = null,
-        DateTime? LastPlayedAt = null);
+        DateTime? LastPlayedAt = null,
+        double? PlaybackPosition = null);
 
     /// <summary>
     /// 浏览文件库目录结构的请求。

FileShare-Services/Services/FileLibrary/FileLibraryEndpointService.cs

@@ -101,6 +101,13 @@ namespace FileShare_Services.Services.FileLibrary
             return ResponseHelper.Succeed();
         }
 
+        /// <inheritdoc />
+        public async Task<IApiResponse> SaveFileProgressAsync(SaveFileProgressRequest request)
+        {
+            await fileLibrary.SaveFileProgressAsync(request.Id, request.Position);
+            return ResponseHelper.Succeed();
+        }
+
         /// <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

@@ -404,6 +404,17 @@ namespace FileShare_Services.Services.FileLibrary
             }
         }
 
+        /// <inheritdoc />
+        public async Task SaveFileProgressAsync(int id, double position, CancellationToken cancellationToken = default)
+        {
+            var record = await db.ManagedFileRecords.FindAsync([id], cancellationToken);
+            if (record is not null)
+            {
+                record.PlaybackPosition = Math.Max(0, position);
+                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。
@@ -559,7 +570,8 @@ namespace FileShare_Services.Services.FileLibrary
                 MediaFileTypes.IsBrowserPlayable(file.Extension),
                 file.ThumbnailId is null ? null : $"/api/thumbnails/{file.ThumbnailId}",
                 file.VideoDuration,
-                file.LastPlayedAt);
+                file.LastPlayedAt,
+                file.PlaybackPosition);
         }
 
     }

FileShare-Services/Services/FileLibrary/IFileLibraryEndpointService.cs

@@ -98,5 +98,12 @@ namespace FileShare_Services.Services.FileLibrary
         /// <param name="request">包含文件 ID 的请求。</param>
         /// <returns>API 响应。</returns>
         Task<IApiResponse> MarkFilePlayedAsync(MarkFilePlayedRequest request);
+
+        /// <summary>
+        /// 保存文件播放进度位置。
+        /// </summary>
+        /// <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);
     }
 }

FileShare-Services/Services/FileLibrary/IFileLibraryService.cs

@@ -113,5 +113,13 @@ namespace FileShare_Services.Services.FileLibrary
         /// <param name="id">文件记录 ID。</param>
         /// <param name="cancellationToken">取消令牌。</param>
         Task MarkFilePlayedAsync(int id, CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// 保存文件的播放进度位置。
+        /// </summary>
+        /// <param name="id">文件记录 ID。</param>
+        /// <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);
     }
 }