fix: make sure the new pattern is appended as a new line (#1264)

Signed-off-by: leo <[email protected]>

Author: love-linger

src/Commands/GitIgnore.cs

@@ -8,7 +8,14 @@ public static void Add(string repo, string pattern)
         {
             var file = Path.Combine(repo, ".gitignore");
             if (!File.Exists(file))
+            {
                 File.WriteAllLines(file, [pattern]);
+                return;
+            }
+
+            var org = File.ReadAllText(file);
+            if (!org.EndsWith('\n'))
+                File.AppendAllLines(file, ["", pattern]);
             else
                 File.AppendAllLines(file, [pattern]);
         }