feat: add phase five operations foundation

Tiku.Application/Jobs/BackgroundJobModels.cs

@@ -0,0 +1,43 @@
+using System.Text.Json;
+using Tiku.Domain.Operations;
+
+namespace Tiku.Application.Jobs;
+
+public sealed record CreateBackgroundJobCommand(
+    Guid TenantId,
+    string JobType,
+    JsonElement Payload,
+    DateTimeOffset? RunAfter = null,
+    int MaxRetries = 3);
+
+public sealed record BackgroundJobItem(
+    Guid Id,
+    Guid TenantId,
+    string JobType,
+    BackgroundJobStatus Status,
+    int RetryCount,
+    int MaxRetries,
+    DateTimeOffset? RunAfter,
+    DateTimeOffset? StartedAt,
+    DateTimeOffset? CompletedAt,
+    string? LastError,
+    Guid? OutputAssetId,
+    JsonElement Result);
+
+public interface IBackgroundJobService
+{
+    Task<BackgroundJobItem> EnqueueAsync(
+        CreateBackgroundJobCommand command,
+        CancellationToken cancellationToken = default);
+
+    Task<int> ProcessPendingAsync(
+        string workerId,
+        int batchSize,
+        CancellationToken cancellationToken = default);
+
+    Task<IReadOnlyCollection<BackgroundJobItem>> ListAsync(
+        Guid tenantId,
+        string? jobType = null,
+        int limit = 50,
+        CancellationToken cancellationToken = default);
+}