Fix version string and add X11 wmclass hint

Version was incorrectly set to 0.1.0-chromatic-quantize
despite nix-support being based on main. Added X11 wmclass
hint alongside Wayland for icon matching on both backends.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: zitongcharliedeng

flake.nix

@@ -140,10 +140,11 @@
             chmod +x $out/bin/midimech
             patchShebangs $out/bin/midimech
 
-            # Wrap to include runtime libraries + set Wayland app ID for icon matching
+            # Wrap to include runtime libraries + set window class for desktop icon matching
             wrapProgram $out/bin/midimech \
               --prefix LD_LIBRARY_PATH : "${runtimeLibs}" \
               --set SDL_VIDEO_WAYLAND_WMCLASS midimech \
+              --set SDL_VIDEO_X11_WMCLASS midimech \
               --set SDL_APP_ID midimech
 
             # Desktop entry for application launchers