feat: add WorkProcessor interfaces and options

- ISearchNotificationService: SignalR notification abstraction in Core
- WorkProcessorOptions: configuration for work processor behavior
- ISearchRepository: Search table operations contract
- ISearchExecutionService: search pipeline orchestration contract

NEW/src/JdeScoping.Core/Interfaces/ISearchNotificationService.cs

@@ -0,0 +1,24 @@
+using JdeScoping.Core.Models.Search;
+
+namespace JdeScoping.Core.Interfaces;
+
+/// <summary>
+/// Interface for SignalR notifications - lives in Core to avoid dependency issues.
+/// Implementation lives in Host/Api layer.
+/// </summary>
+public interface ISearchNotificationService
+{
+    /// <summary>
+    /// Notifies clients of search status update.
+    /// </summary>
+    /// <param name="search">The search with updated status.</param>
+    /// <param name="ct">Cancellation token.</param>
+    Task NotifySearchUpdateAsync(Search search, CancellationToken ct = default);
+
+    /// <summary>
+    /// Notifies clients of work processor status change.
+    /// </summary>
+    /// <param name="status">Status message.</param>
+    /// <param name="ct">Cancellation token.</param>
+    Task NotifyStatusAsync(string status, CancellationToken ct = default);
+}

NEW/src/JdeScoping.DataSync/Contracts/ISearchExecutionService.cs

@@ -0,0 +1,17 @@
+using JdeScoping.Core.Models.Search;
+
+namespace JdeScoping.DataSync.Contracts;
+
+/// <summary>
+/// Interface for search execution pipeline orchestration.
+/// </summary>
+public interface ISearchExecutionService
+{
+    /// <summary>
+    /// Executes the complete search pipeline: query, Excel generation, result storage.
+    /// Handles status transitions and notifications.
+    /// </summary>
+    /// <param name="search">The search to execute.</param>
+    /// <param name="ct">Cancellation token.</param>
+    Task ExecuteSearchAsync(Search search, CancellationToken ct = default);
+}

NEW/src/JdeScoping.DataSync/Contracts/ISearchRepository.cs

@@ -0,0 +1,40 @@
+using JdeScoping.Core.Models.Search;
+
+namespace JdeScoping.DataSync.Contracts;
+
+/// <summary>
+/// Repository interface for Search table operations.
+/// </summary>
+public interface ISearchRepository
+{
+    /// <summary>
+    /// Gets the next queued search ordered by SubmitDT (FIFO).
+    /// </summary>
+    /// <param name="ct">Cancellation token.</param>
+    /// <returns>The next queued search, or null if none.</returns>
+    Task<Search?> GetNextQueuedSearchAsync(CancellationToken ct = default);
+
+    /// <summary>
+    /// Resets partial searches (Running but not Ended) back to Queued status.
+    /// Called at service startup to handle interrupted operations.
+    /// </summary>
+    /// <param name="ct">Cancellation token.</param>
+    /// <returns>Count of reset searches.</returns>
+    Task<int> ResetPartialSearchesAsync(CancellationToken ct = default);
+
+    /// <summary>
+    /// Marks search as Running with StartDT = now.
+    /// </summary>
+    /// <param name="searchId">Search ID.</param>
+    /// <param name="ct">Cancellation token.</param>
+    Task StartSearchAsync(int searchId, CancellationToken ct = default);
+
+    /// <summary>
+    /// Marks search as Ended (success) or Error (failure) with EndDT and optional Results.
+    /// </summary>
+    /// <param name="searchId">Search ID.</param>
+    /// <param name="success">Whether search completed successfully.</param>
+    /// <param name="results">Excel file bytes (null on failure).</param>
+    /// <param name="ct">Cancellation token.</param>
+    Task CompleteSearchAsync(int searchId, bool success, byte[]? results, CancellationToken ct = default);
+}

NEW/src/JdeScoping.DataSync/Options/WorkProcessorOptions.cs

@@ -0,0 +1,37 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace JdeScoping.DataSync.Options;
+
+/// <summary>
+/// Configuration options for the WorkProcessor background service.
+/// </summary>
+public class WorkProcessorOptions
+{
+    /// <summary>
+    /// Configuration section name.
+    /// </summary>
+    public const string SectionName = "WorkProcessor";
+
+    /// <summary>
+    /// Whether the work processor is enabled. Default: true.
+    /// </summary>
+    public bool Enabled { get; set; } = true;
+
+    /// <summary>
+    /// Interval between work cycles. Default: 5 seconds.
+    /// </summary>
+    [Range(typeof(TimeSpan), "00:00:01", "01:00:00")]
+    public TimeSpan WorkInterval { get; set; } = TimeSpan.FromSeconds(5);
+
+    /// <summary>
+    /// Search execution timeout. Default: 30 minutes.
+    /// </summary>
+    [Range(typeof(TimeSpan), "00:01:00", "04:00:00")]
+    public TimeSpan SearchTimeout { get; set; } = TimeSpan.FromMinutes(30);
+
+    /// <summary>
+    /// Number of days to retain DataUpdate records. Default: 30.
+    /// </summary>
+    [Range(1, 365)]
+    public int PurgeRetentionDays { get; set; } = 30;
+}