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.

tests/ClaudeDo.Worker.Tests/Infrastructure/FakeClaudeStreamTransport.cs

@@ -0,0 +1,47 @@
+using ClaudeDo.Worker.Runner.Interfaces;
+
+namespace ClaudeDo.Worker.Tests.Infrastructure;
+
+public sealed class FakeClaudeStreamTransport : IClaudeStreamTransport
+{
+    public List<string> Written { get; } = [];
+    public bool Killed { get; private set; }
+    public bool Started { get; private set; }
+
+    public event Func<string, Task>? LineReceived;
+    public event Func<string, Task>? StderrReceived;
+
+    public Task StartAsync(IReadOnlyList<string> args, string workingDirectory, CancellationToken ct)
+    {
+        Started = true;
+        return Task.CompletedTask;
+    }
+
+    public Task WriteLineAsync(string jsonLine, CancellationToken ct)
+    {
+        Written.Add(jsonLine);
+        return Task.CompletedTask;
+    }
+
+    public void Kill() => Killed = true;
+
+    public Task WaitForExitAsync() => Task.CompletedTask;
+
+    public ValueTask DisposeAsync() => ValueTask.CompletedTask;
+
+    // Test helper: push a simulated stdout line to all LineReceived subscribers.
+    public async Task PushLineAsync(string line)
+    {
+        var handler = LineReceived;
+        if (handler is not null)
+            await handler(line);
+    }
+
+    // Test helper: push a simulated stderr line.
+    public async Task PushStderrAsync(string line)
+    {
+        var handler = StderrReceived;
+        if (handler is not null)
+            await handler(line);
+    }
+}