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.Ui/Services/Interfaces/IPrimeScheduleApi.cs

@@ -0,0 +1,8 @@
+namespace ClaudeDo.Ui.Services;
+
+public interface IPrimeScheduleApi
+{
+    Task<List<PrimeScheduleDto>> ListAsync();
+    Task<PrimeScheduleDto?> UpsertAsync(PrimeScheduleDto dto);
+    Task DeleteAsync(Guid id);
+}