fixed GSA writing, added always-edit button and search in file and for file

GsaEditor.Core/IO/GsaWriter.cs

@@ -15,6 +15,12 @@ public static class GsaWriter
     /// <summary>Magic word for the NARD (enhanced) format.</summary>
     private const uint MAGIC_NARD = 0x4E415244;
 
+    /// <summary>
+    /// End-of-archive terminator written where the next entry's alias length would be.
+    /// The engine's sequential reader stops when it hits this invalid length.
+    /// </summary>
+    private const uint TERMINATOR = 0xFFFFFFFF;
+
     /// <summary>
     /// Writes the archive to the specified file path.
     /// </summary>
@@ -53,6 +59,11 @@ public static class GsaWriter
         {
             WriteEntry(writer, entry, archive);
         }
+
+        // Write the end-of-archive terminator, aligned like an entry header
+        if (archive.Format == GsaFormat.NARD && archive.OffsetPadding > 0)
+            WritePadding(writer, archive.OffsetPadding);
+        writer.Write(TERMINATOR);
     }
 
     /// <summary>