feat(ui): PowerUse-Einstellungen nach Settings -> Ausfuehrung verschieben

Schalter, Zeitfenster und Handoff-Prozent lagen im Usage-Monitor und mussten
in SettingsModalViewModel nur load->save durchgeschleift werden, damit ein
Settings-Speichern sie nicht zurueckwirft. Jetzt gehoeren sie dem General-Tab,
der Monitor ist wieder nur Anzeige + Threshold-Drag, und "Jetzt aktualisieren"
sitzt als Icon in der Titelleiste (neuer ModalShell.HeaderActions-Slot).

tests/ClaudeDo.Ui.Tests/ViewModels/SettingsModalViewModelTests.cs

@@ -131,6 +131,38 @@ public class SettingsModalViewModelTests : IDisposable
         Assert.Equal(77, worker.Saved.UsageGateSevenDayPct);
     }
 
+    [Fact]
+    public async Task PowerUse_survives_a_load_edit_save_round_trip()
+    {
+        // PowerUse moved off the usage monitor onto this tab, so Settings is now its only writer.
+        // A binding that doesn't reach General silently resets the switch to the record default.
+        var worker = new FakeWorker
+        {
+            AppToReturn = DtoWith(80, 90) with
+            {
+                PowerUseEnabled = true,
+                PowerUseWindowStart = "18:00",
+                PowerUseWindowEnd = "06:00",
+                PowerUseHandoffPct = 88,
+            },
+        };
+        var vm = MakeVm(worker);
+        await vm.LoadAsync();
+
+        Assert.True(vm.General.PowerUseEnabled);
+        Assert.Equal("18:00", vm.General.PowerUseWindowStart);
+        Assert.Equal(88, vm.General.PowerUseHandoffPct);
+
+        // A typo in the window is normalized to null on save, not stored as a fake window.
+        vm.General.PowerUseWindowEnd = "not a time";
+        await vm.SaveCommand.ExecuteAsync(null);
+
+        Assert.True(worker.Saved!.PowerUseEnabled);
+        Assert.Equal("18:00", worker.Saved.PowerUseWindowStart);
+        Assert.Null(worker.Saved.PowerUseWindowEnd);
+        Assert.Equal(88, worker.Saved.PowerUseHandoffPct);
+    }
+
     [Fact]
     public async Task HasLinkedRepo_false_when_no_list_has_a_working_dir()
     {

tests/ClaudeDo.Worker.Tests/Hub/PowerUseSettingsHubTests.cs

@@ -4,9 +4,8 @@ using Xunit;
 
 namespace ClaudeDo.Worker.Tests.Hub;
 
-/// The PowerUse window and handoff threshold are edited on the usage monitor, but Settings→General
-/// rebuilds the whole DTO positionally on save. So the contract that matters is: whatever
-/// GetAppSettings hands out, feeding it straight back must change nothing.
+/// Settings rebuilds the whole AppSettings DTO positionally on save, so the contract that matters
+/// is: whatever GetAppSettings hands out, feeding it straight back must change nothing.
 public sealed class PowerUseSettingsHubTests : IDisposable
 {
     private readonly DbFixture _db = new();

tests/ClaudeDo.Worker.Tests/Runner/HandlerRestartCoordinatorTests.cs

@@ -72,8 +72,8 @@ public sealed class HandlerRestartCoordinatorTests : IDisposable
             });
             await ctx.SaveChangesAsync();
 
-            // Written straight to the row: AppSettingsRepository.UpdateAsync deliberately doesn't
-            // copy PowerUseEnabled (the usage monitor owns that toggle, not the settings modal).
+            // Written straight to the row so the fixture doesn't depend on the repository's
+            // clamping/normalizing copy block.
             await new AppSettingsRepository(ctx).GetAsync(); // materializes the singleton row
             var settings = await ctx.AppSettings.FirstAsync(s => s.Id == AppSettingsEntity.SingletonId);
             settings.PowerUseEnabled = powerUseEnabled;

tests/ClaudeDo.Worker.Tests/Runner/HandlerUsageGuardTests.cs

@@ -68,8 +68,8 @@ public sealed class HandlerUsageGuardTests : IDisposable
             });
             await ctx.SaveChangesAsync();
 
-            // Written straight to the row: AppSettingsRepository.UpdateAsync deliberately doesn't
-            // copy PowerUseEnabled (the usage monitor owns that toggle, not the settings modal).
+            // Written straight to the row so the fixture doesn't depend on the repository's
+            // clamping/normalizing copy block.
             await new AppSettingsRepository(ctx).GetAsync();
             var settings = await ctx.AppSettings.FirstAsync(s => s.Id == AppSettingsEntity.SingletonId);
             settings.PowerUseEnabled = powerUseEnabled;