feat: add asset access signing endpoints

Tiku.Application/Assets/AssetAccessModels.cs

@@ -0,0 +1,40 @@
+using System.Text.Json;
+using Tiku.Application.Storage;
+using Tiku.Domain.Content;
+
+namespace Tiku.Application.Assets;
+
+public sealed record AssetAccessRequest(
+    Guid TenantId,
+    Guid AssetId,
+    Guid? UserId,
+    string? IpAddress,
+    string? UserAgent,
+    TimeSpan? RequestedExpiresIn = null);
+
+public sealed record AssetAccessResultModel(
+    ContentAssetAccessSummary Item,
+    AssetAccessPrincipal Access,
+    ObjectStorageSignedUrl Url,
+    JsonElement Watermark);
+
+public sealed record ContentAssetAccessSummary(
+    Guid Id,
+    ContentAssetType AssetType,
+    string? Title,
+    string? FileName,
+    string? PreviewUrl,
+    AssetUploadStatus UploadStatus,
+    AssetSecurityScanStatus SecurityScanStatus,
+    AssetPreviewStatus PreviewStatus,
+    ContentVisibility Visibility);
+
+public sealed record AssetAccessPrincipal(
+    Guid? UserId,
+    bool IsMember,
+    bool HasSvip);
+
+public sealed class AssetAccessException(string message, string code) : InvalidOperationException(message)
+{
+    public string Code { get; } = code;
+}

Tiku.Application/Assets/IAssetAccessService.cs

@@ -0,0 +1,12 @@
+namespace Tiku.Application.Assets;
+
+public interface IAssetAccessService
+{
+    Task<AssetAccessResultModel> DownloadAsync(
+        AssetAccessRequest request,
+        CancellationToken cancellationToken = default);
+
+    Task<AssetAccessResultModel> PreviewAsync(
+        AssetAccessRequest request,
+        CancellationToken cancellationToken = default);
+}