feat(worker): AskUser MCP tool so a running task can ask the user mid-run

A running task can call mcp__claudedo_run__AskUser(question) to block (up to 3
min) on a human answer. PendingQuestionRegistry holds the pending question +
TaskCompletionSource; the tool broadcasts TaskQuestionAsked, awaits the answer
(WorkerHub.AnswerTaskQuestion resolves it), and returns it as the tool result —
or a 'proceed on your judgment' fallback on timeout. The run stays Running
throughout (no status/schema change). ClaudeProcess raises MCP_TOOL_TIMEOUT so
the 60s HTTP-MCP cap doesn't kill the wait; the run MCP is now wired for every
task, not just standalone ones. System prompt updated to reconcile 'unattended'.

src/ClaudeDo.Worker/Program.cs

@@ -72,6 +72,7 @@ builder.Services.AddSingleton<GitService>();
 builder.Services.AddSingleton<WorktreeManager>();
 builder.Services.AddSingleton<ClaudeArgsBuilder>();
 builder.Services.AddSingleton<TaskRunTokenRegistry>();
+builder.Services.AddSingleton<PendingQuestionRegistry>();
 builder.Services.AddSingleton<TaskRunner>();
 builder.Services.AddSingleton<WorktreeMaintenanceService>();
 builder.Services.AddSingleton<TaskResetService>();