feat: add QML/Qt6 support system-wide

- Add qt6.full (includes qmlls language server) and libclang
- Configure QT_QPA_PLATFORM_PLUGIN_PATH and QML_IMPORT_PATH environment
  variables
- Link Qt6 share directory for proper resource discovery

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

packages.nix

@@ -30,5 +30,9 @@ with pkgs;
     smartmontools
     gsmartcontrol
     parted
+
+    # qml/qt6
+    qt6.full
+    libclang
   ];
 }