Health banner Library-only (mirror of footer scoping)

Same logic as the footer : the health pills make sense only when the
user is on the Library page. On Reports / Documentation, the WebView
takes the full content area and the system-status row would just steal
vertical space without adding value (and arguably distracts from the
embedded site).

New ShowHealthBanner = HasHealthIndicators && IsLibrary, with
NotifyPropertyChangedFor on CurrentPage so the row collapses/reveals
on tab switch like the footer already does.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/PSLauncher.App/ViewModels/MainViewModel.cs

@@ -74,6 +74,13 @@ public sealed partial class MainViewModel : ObservableObject
     public ObservableCollection<HealthIndicatorViewModel> HealthIndicators { get; } = new();
     public bool HasHealthIndicators => HealthIndicators.Count > 0;
 
+    /// <summary>
+    /// Le bandeau santé n'a de sens que sur la page Library — Reports et
+    /// Documentation sont des WebView pleine-page où afficher des pills
+    /// de monitoring système n'apporte rien et coupe visuellement.
+    /// </summary>
+    public bool ShowHealthBanner => HasHealthIndicators && IsLibrary;
+
     [ObservableProperty]
     [NotifyPropertyChangedFor(nameof(HasFeaturedVersion))]
     [NotifyPropertyChangedFor(nameof(HasOtherVersions))]
@@ -110,6 +117,7 @@ public sealed partial class MainViewModel : ObservableObject
     [NotifyPropertyChangedFor(nameof(IsDocumentation))]
     [NotifyPropertyChangedFor(nameof(FooterVisibility))]
     [NotifyPropertyChangedFor(nameof(FooterText))]
+    [NotifyPropertyChangedFor(nameof(ShowHealthBanner))]
     private LauncherPage _currentPage = LauncherPage.Library;
 
     public bool IsLibrary       => CurrentPage == LauncherPage.Library;
@@ -307,6 +315,7 @@ public sealed partial class MainViewModel : ObservableObject
         foreach (var entry in _config.HealthChecks.Checks)
             HealthIndicators.Add(new HealthIndicatorViewModel(entry));
         OnPropertyChanged(nameof(HasHealthIndicators));
+        OnPropertyChanged(nameof(ShowHealthBanner));
     }
 
     /// <summary>