Add UTF-8 detection with ASCII fallback for terminal compatibility

- Detect Windows Terminal (WT_SESSION), PowerShell, and non-Windows
  terminals to enable UTF-8 output encoding automatically
- Use ★ and → when UTF-8 is supported, fall back to * and -> on cmd.exe
- Set Console.OutputEncoding = UTF8 at startup for capable terminals

src/OpenTheBox/Program.cs

@@ -35,6 +35,8 @@ public static class Program
 
     public static async Task Main(string[] args)
     {
+        UnicodeSupport.Initialize();
+
         // --snapshot N: directly load snapshot_N save and start playing
         int snapshotSlot = 0;
         var snapshotIdx = Array.IndexOf(args, "--snapshot");
@@ -521,8 +523,8 @@ public static class Program
 
                 case ResourceChangedEvent resEvt:
                     var resName = _loc.Get($"resource.{resEvt.Type.ToString().ToLower()}");
-                    _renderer.ShowMessage($"{resName}: {resEvt.OldValue} -> {resEvt.NewValue}");
+                    _renderer.ShowMessage($"{resName}: {resEvt.OldValue} {UnicodeSupport.Arrow} {resEvt.NewValue}");
-                    AddEventLog($"{resName}: {resEvt.OldValue} -> {resEvt.NewValue}");
+                    AddEventLog($"{resName}: {resEvt.OldValue} {UnicodeSupport.Arrow} {resEvt.NewValue}");
                     break;
 
                 case MessageEvent msgEvt:
@@ -758,8 +760,8 @@ public static class Program
                                 ? _loc.Get("inventory.item_used_qty", itemName, remaining.ToString())
                                 : _loc.Get("inventory.item_used", itemName);
                             _renderer.ShowMessage(usedMsg);
-                            _renderer.ShowMessage($"{resName}: {resEvt.OldValue} -> {resEvt.NewValue}");
+                            _renderer.ShowMessage($"{resName}: {resEvt.OldValue} {UnicodeSupport.Arrow} {resEvt.NewValue}");
-                            AddEventLog($"{itemName} -> {resName} {resEvt.OldValue}->{resEvt.NewValue}");
+                            AddEventLog($"{itemName} {UnicodeSupport.Arrow} {resName} {resEvt.OldValue}{UnicodeSupport.Arrow}{resEvt.NewValue}");
                             break;
                         case MessageEvent msgEvt:
                             _renderer.ShowMessage(_loc.Get(msgEvt.MessageKey, msgEvt.Args ?? []));
@@ -784,7 +786,7 @@ public static class Program
                             break;
                         case ResourceChangedEvent resEvt:
                             var cookieResName = _loc.Get($"resource.{resEvt.Type.ToString().ToLower()}");
-                            _renderer.ShowMessage($"{cookieResName}: {resEvt.OldValue} → {resEvt.NewValue}");
+                            _renderer.ShowMessage($"{cookieResName}: {resEvt.OldValue} {UnicodeSupport.Arrow} {resEvt.NewValue}");
                             break;
                         case MessageEvent msgEvt:
                             _renderer.ShowMessage(_loc.Get(msgEvt.MessageKey, msgEvt.Args ?? []));

src/OpenTheBox/Rendering/SpectreRenderer.cs

@@ -323,7 +323,8 @@ public sealed class SpectreRenderer : IRenderer
     {
         if (_context.HasColors)
         {
-            var panel = new Panel($"[bold yellow]* {Markup.Escape(featureName)} *[/]")
+            var star = UnicodeSupport.Star;
+            var panel = new Panel($"[bold yellow]{star} {Markup.Escape(featureName)} {star}[/]")
                 .Border(BoxBorder.Double)
                 .BorderStyle(new Style(Color.Yellow))
                 .Padding(2, 0)
@@ -333,7 +334,7 @@ public sealed class SpectreRenderer : IRenderer
         else
         {
             Console.WriteLine("========================================");
-            Console.WriteLine($"  * {featureName} *");
+            Console.WriteLine($"  {UnicodeSupport.Star} {featureName} {UnicodeSupport.Star}");
             Console.WriteLine("========================================");
         }
     }
@@ -429,14 +430,18 @@ public sealed class SpectreRenderer : IRenderer
     /// <summary>
     /// Returns rarity star prefix for Rare and above items.
     /// </summary>
-    private static string RarityStars(string rarity) => rarity.ToLowerInvariant() switch
+    private static string RarityStars(string rarity)
     {
-        "rare" => "* ",
+        var s = UnicodeSupport.Star;
-        "epic" => "** ",
+        return rarity.ToLowerInvariant() switch
-        "legendary" => "*** ",
+        {
-        "mythic" => "**** ",
+            "rare" => $"{s} ",
-        _ => ""
+            "epic" => $"{s}{s} ",
-    };
+            "legendary" => $"{s}{s}{s} ",
+            "mythic" => $"{s}{s}{s}{s} ",
+            _ => ""
+        };
+    }
 
     private static Color RarityColorValue(string rarity) => rarity.ToLowerInvariant() switch
     {

src/OpenTheBox/Rendering/UnicodeSupport.cs

@@ -0,0 +1,75 @@
+using System.Text;
+
+namespace OpenTheBox.Rendering;
+
+/// <summary>
+/// Detects whether the terminal supports UTF-8 output and provides
+/// glyph accessors that return Unicode or ASCII equivalents accordingly.
+/// Call <see cref="Initialize"/> once at startup.
+/// </summary>
+public static class UnicodeSupport
+{
+    /// <summary>True when the terminal accepts UTF-8 characters beyond CP437.</summary>
+    public static bool IsUtf8 { get; private set; }
+
+    // ── Glyphs ──────────────────────────────────────────────────────────
+
+    /// <summary>Arrow: → or -></summary>
+    public static string Arrow => IsUtf8 ? "→" : "->";
+
+    /// <summary>Star for rarity prefix: ★ or *</summary>
+    public static string Star => IsUtf8 ? "★" : "*";
+
+    /// <summary>
+    /// Attempts to set UTF-8 output encoding and detects whether the
+    /// terminal actually supports it (Windows Terminal, PowerShell, etc.).
+    /// </summary>
+    public static void Initialize()
+    {
+        // Windows Terminal always sets WT_SESSION
+        if (Environment.GetEnvironmentVariable("WT_SESSION") is not null)
+        {
+            EnableUtf8();
+            return;
+        }
+
+        // Modern PowerShell (pwsh) or Windows PowerShell with PSModulePath
+        // typically supports UTF-8 when we set the encoding
+        if (Environment.GetEnvironmentVariable("PSModulePath") is not null)
+        {
+            EnableUtf8();
+            return;
+        }
+
+        // Non-Windows platforms (Linux, macOS) generally support UTF-8
+        if (!OperatingSystem.IsWindows())
+        {
+            EnableUtf8();
+            return;
+        }
+
+        // Fallback: try to set UTF-8 and check if it stuck
+        try
+        {
+            Console.OutputEncoding = Encoding.UTF8;
+            IsUtf8 = Console.OutputEncoding.CodePage == 65001;
+        }
+        catch
+        {
+            IsUtf8 = false;
+        }
+    }
+
+    private static void EnableUtf8()
+    {
+        try
+        {
+            Console.OutputEncoding = Encoding.UTF8;
+        }
+        catch
+        {
+            // Ignore if setting encoding fails
+        }
+        IsUtf8 = true;
+    }
+}