chore: housekeeping — linter & formatter setup

Add .prettierrc.json, .markdownlint.json, .yamllint.yaml, .gitattributes
Run CSharpier, Prettier and markdownlint across the entire codebase.
No logic changes — formatting, using order and line endings only.

HellionChat/Util/IconUtil.cs

@@ -31,7 +31,8 @@ public readonly unsafe ref struct GfdFileView
     private ref readonly GfdHeader Header => ref MemoryMarshal.AsRef<GfdHeader>(Span);
 
     /// <summary>Gets the entries.</summary>
-    private ReadOnlySpan<GfdEntry> Entries => MemoryMarshal.Cast<byte, GfdEntry>(Span[sizeof(GfdHeader)..]);
+    private ReadOnlySpan<GfdEntry> Entries =>
+        MemoryMarshal.Cast<byte, GfdEntry>(Span[sizeof(GfdHeader)..]);
 
     /// <summary>Attempts to get an entry.</summary>
     /// <param name="iconId">The icon ID.</param>
@@ -153,8 +154,6 @@ public readonly unsafe ref struct GfdFileView
     }
 }
 
-
-
 internal static class IconUtil
 {
     private static byte[]? GfdFile;
@@ -164,8 +163,11 @@ internal static class IconUtil
         {
             if (GfdFile is null)
             {
-                var file = Plugin.DataManager.GetFile("common/font/gfdata.gfd")
-                    ?? throw new FileNotFoundException("Failed to load common/font/gfdata.gfd from the game data.");
+                var file =
+                    Plugin.DataManager.GetFile("common/font/gfdata.gfd")
+                    ?? throw new FileNotFoundException(
+                        "Failed to load common/font/gfdata.gfd from the game data."
+                    );
                 GfdFile = file.Data;
             }
             return new GfdFileView(GfdFile);