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);
+}