refactor: extract interfaces to Interfaces folders and consolidate filters

Move interface declarations into per-area Interfaces/ subfolders, merge the
small task-list filter classes into StatusFilter/SmartFlagFilter, and simplify
related services, converters and hub DTO handling.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/ClaudeDo.Worker/Queue/Interfaces/IQueuePicker.cs

@@ -0,0 +1,12 @@
+using ClaudeDo.Data.Models;
+
+namespace ClaudeDo.Worker.Queue;
+
+/// <summary>
+/// Atomic queue claim. Returns the claimed task (already flipped to Running with
+/// StartedAt set) or null if no eligible task is available.
+/// </summary>
+public interface IQueuePicker
+{
+    Task<TaskEntity?> ClaimNextAsync(DateTime now, CancellationToken ct);
+}

src/ClaudeDo.Worker/Queue/Interfaces/IQueueWaker.cs

@@ -0,0 +1,11 @@
+namespace ClaudeDo.Worker.Queue;
+
+/// <summary>
+/// Signals the queue dispatcher to check for new work. Wake() is non-blocking and
+/// idempotent — multiple calls before the dispatcher consumes the signal collapse
+/// into a single wake-up.
+/// </summary>
+public interface IQueueWaker
+{
+    void Wake();
+}