feat(tasks): mark tasks and lists as manual

Reminders written down as todos had no home: every task looked like Claude work.
A manual task now shows a MANUAL badge and hides send-to-queue, refine and the
planning session; the queue picker, daily prep and the list handler all skip it,
with a TaskStateService guard so the MCP surface and hub cannot start one either.
Opening a hand-driven ConPTY session stays available on purpose.

A list can be marked manual in its settings, which makes tasks created there
(UI and MCP add_task) start out manual. Toggle per task from its context menu.

tests/ClaudeDo.Worker.Tests/State/TaskStateServiceTests.cs

@@ -41,7 +41,8 @@ public sealed class TaskStateServiceTests : IDisposable
         string? parentId = null,
         int sortOrder = 0,
         string? blockedBy = null,
-        PlanningPhase phase = PlanningPhase.None)
+        PlanningPhase phase = PlanningPhase.None,
+        bool isManual = false)
     {
         var id = Guid.NewGuid().ToString();
         await using var ctx = _factory.CreateDbContext();
@@ -56,6 +57,7 @@ public sealed class TaskStateServiceTests : IDisposable
             ParentTaskId = parentId,
             SortOrder = sortOrder,
             BlockedByTaskId = blockedBy,
+            IsManual = isManual,
         });
         await ctx.SaveChangesAsync();
         return id;
@@ -89,6 +91,30 @@ public sealed class TaskStateServiceTests : IDisposable
         Assert.Contains(_built.Hub.Proxy.Calls, c => c.Method == "TaskUpdated");
     }
 
+    [Fact]
+    public async Task EnqueueAsync_ManualTask_Rejected_AndStaysIdle()
+    {
+        var id = await SeedTaskAsync(TaskStatus.Idle, isManual: true);
+
+        var result = await _sut.EnqueueAsync(id, default);
+
+        Assert.False(result.Ok);
+        Assert.Contains("Manual task", result.Reason);
+        Assert.Equal(TaskStatus.Idle, await GetStatusAsync(id));
+    }
+
+    [Fact]
+    public async Task StartRunningAsync_ManualTask_Rejected_AndStaysIdle()
+    {
+        var id = await SeedTaskAsync(TaskStatus.Idle, isManual: true);
+
+        var result = await _sut.StartRunningAsync(id, DateTime.UtcNow, default);
+
+        Assert.False(result.Ok);
+        Assert.Contains("Manual task", result.Reason);
+        Assert.Equal(TaskStatus.Idle, await GetStatusAsync(id));
+    }
+
     [Fact]
     public async Task EnqueueAsync_FromRunning_Rejects_AndDoesNotMutate()
     {