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/Runner/Interfaces/IClaudeProcess.cs

@@ -0,0 +1,11 @@
+namespace ClaudeDo.Worker.Runner;
+
+public interface IClaudeProcess
+{
+    Task<RunResult> RunAsync(
+        string arguments,
+        string prompt,
+        string workingDirectory,
+        Func<string, Task> onStdoutLine,
+        CancellationToken ct);
+}