feat(ui): color and acknowledge pinned log errors

Add independent AppLog message types and explicit Class 1/2 severity. Wrap and color log rows, pin Class 1 above Class 2, and let acknowledgement return entries to the current-launch timeline without changing file format or rotation.

Ref: https://logtape.org/manual/levels

Helpers/AppLog.cs

@@ -2,6 +2,24 @@ using System.IO;
 
 namespace ytLive.Helpers;
 
+/// <summary>Presentation category; independent from the entry's attention class.</summary>
+public enum AppLogMessageType
+{
+    Information,
+    Success,
+    Warning,
+    Error,
+}
+
+/// <summary>Explicit attention priority, assigned by the writer rather than inferred from text or source.</summary>
+public enum AppLogErrorClass
+{
+    /// <summary>Fatal or unhandled failure; highest priority.</summary>
+    Class1 = 1,
+    /// <summary>Recoverable failure that still requires attention.</summary>
+    Class2 = 2,
+}
+
 /// <summary>
 /// Minimal file logger used to diagnose startup/shutdown crashes on Windows,
 /// where the WPF app has no visible console. Writes to
@@ -39,6 +57,15 @@ public static class AppLog
     }
 
     public static void Write(string message)
+        => Write(message, AppLogMessageType.Information);
+
+    public static void WriteWarning(string message)
+        => Write(message, AppLogMessageType.Warning);
+
+    public static void WriteSuccess(string message)
+        => Write(message, AppLogMessageType.Success);
+
+    public static void Write(string message, AppLogMessageType type, AppLogErrorClass? errorClass = null)
     {
         try
         {
@@ -46,7 +73,9 @@ public static class AppLog
             {
                 var entry = new AppLogEntry(
                     ++_nextSequence,
-                    $"{DateTime.Now:yyyy-MM-dd HH:mm:ss.fff} {message}");
+                    $"{DateTime.Now:yyyy-MM-dd HH:mm:ss.fff} {message}",
+                    type,
+                    errorClass);
                 CurrentLaunchEntries.Add(entry);
                 if (CurrentLaunchEntries.Count > CurrentLaunchEntryLimit)
                     CurrentLaunchEntries.RemoveAt(0);
@@ -65,8 +94,29 @@ public static class AppLog
 
     public static void Write(Exception exception, string message)
     {
-        Write($"{message}: {exception}");
+        Write($"{message}: {exception}", AppLogMessageType.Error);
     }
+
+    public static void Write(Exception exception, string message, AppLogErrorClass errorClass)
+        => Write($"{message}: {exception}", AppLogMessageType.Error, errorClass);
 }
 
-public sealed record AppLogEntry(long Sequence, string Text);
+public sealed record AppLogEntry(long Sequence, string Text, AppLogMessageType Type,
+    AppLogErrorClass? ErrorClass)
+{
+    public string? ErrorClassLabel => ErrorClass switch
+    {
+        AppLogErrorClass.Class1 => "CLASS 1",
+        AppLogErrorClass.Class2 => "CLASS 2",
+        _ => null,
+    };
+
+    public string TypeLabel => ErrorClassLabel ?? Type switch
+    {
+        AppLogMessageType.Information => "INFO",
+        AppLogMessageType.Success => "SUCCESS",
+        AppLogMessageType.Warning => "WARNING",
+        AppLogMessageType.Error => "ERROR",
+        _ => Type.ToString().ToUpperInvariant(),
+    };
+}

Helpers/index.md

@@ -6,7 +6,7 @@ Cross-cutting utilities. See [`schema.md`](../schema.md) for the memory-map conv
 |------|---------|
 | `ViewModelBase.cs` | `INotifyPropertyChanged` + `SetProperty<T>()` — base for all ViewModels |
 | `RelayCommand.cs` | `ICommand` implementation for all button actions |
-| `AppLog.cs` | File logger to `%APPDATA%\ytLlive\startup.log`; startup checkpoints + unhandled-exception capture. Size-capped: rolls to `startup.1.log` at 5 MB (TASK 55). Also keeps the newest 500 formatted entries in a process-local buffer for the Logs tab; it never loads prior-launch file contents |
+| `AppLog.cs` | File logger to `%APPDATA%\ytLlive\startup.log`; startup checkpoints + unhandled-exception capture. Size-capped: rolls to `startup.1.log` at 5 MB (TASK 55). Also keeps the newest 500 formatted entries in a process-local buffer for the Logs tab, with independent message type and explicit Class 1/2 severity metadata; it never loads prior-launch file contents |
 | `LogRotation.cs` | The size-capped-rotation policy as a pure function over a path: roll `startup.log` → `startup.1.log` when it passes the cap, keeping N rolled copies. Separate from `AppLog` so the logger's 156-call-site surface never changes and the rule is testable alone (TASK 55) |
 | `FocusPreservingListBox.cs` | `ListBox` subclass that keeps selection/focus coherent when the selected item is deleted; `IsSelectable` predicate skips hidden scenes; drag-reorder guard |
 | `OAuthCredentials.cs` | Baked-in Google OAuth client ID/secret (desktop app; loopback callback) |