feat(worker): persistent streaming Claude session + live session registry

StreamingClaudeSession drives claude --input-format stream-json over a kept-
open stdin: sends user messages, interrupts the in-flight turn via the verified
control_request protocol, and tracks turn state from result events (treating an
interrupt-aborted error_during_execution result as turn-ended). IClaudeStreamTransport
abstracts the process I/O so it is unit-tested with a fake (no real claude).
LiveSessionRegistry maps taskId -> live session for the hub to route into.

Backs the upcoming in-app interactive sessions; autonomous task execution untouched.

src/ClaudeDo.Worker/Runner/Interfaces/IClaudeStreamTransport.cs

@@ -0,0 +1,11 @@
+namespace ClaudeDo.Worker.Runner.Interfaces;
+
+public interface IClaudeStreamTransport : IAsyncDisposable
+{
+    Task StartAsync(IReadOnlyList<string> args, string workingDirectory, CancellationToken ct);
+    Task WriteLineAsync(string jsonLine, CancellationToken ct);
+    event Func<string, Task>? LineReceived;
+    event Func<string, Task>? StderrReceived;
+    void Kill();
+    Task WaitForExitAsync();
+}