Add Noctalia shell with Quickshell overview

- Add `noctalia` input to flake and lock it in `flake.lock`.
- Include `noctalia` and `quickshell` modules in `flake.nix`.
- Extend core packages to accept `inputs` and `system`; add
  `quickshell.nix`
  with required Qt6 packages and environment variables.
- Enable `upower` service for battery handling.
- Add home modules `noctalia.nix` and `overview.nix` (QML UI, README,
  assets, widgets, services) to provide a workspace overview.
- Comment out unused rofi and web‑search binds; update `exec‑once` to
  start
  the overview daemon and `noctalia-shell`.
- Provide `restart.noctalia` script and its Nix wrapper.
- Enable `noctalia-shell` in `stylix` configuration.

modules/core/quickshell.nix

@@ -0,0 +1,30 @@
+{pkgs, ...}: {
+  environment = {
+    systemPackages = with pkgs; [
+      quickshell
+
+      # Qt6 related kits（for slove Qt5Compat problem）
+      qt6.qt5compat
+      qt6.qtbase
+      qt6.qtquick3d
+      qt6.qtwayland
+      qt6.qtdeclarative
+      qt6.qtsvg
+
+      # alternate options
+      # libsForQt5.qt5compat
+      kdePackages.qt5compat
+      libsForQt5.qt5.qtgraphicaleffects
+    ];
+    # necessary environment variables
+    variables = {
+      QML_IMPORT_PATH = "${pkgs.qt6.qt5compat}/lib/qt-6/qml:${pkgs.qt6.qtbase}/lib/qt-6/qml";
+      QML2_IMPORT_PATH = "${pkgs.qt6.qt5compat}/lib/qt-6/qml:${pkgs.qt6.qtbase}/lib/qt-6/qml";
+    };
+    # make sure the Qt application is working properly
+    sessionVariables = {
+      QT_QPA_PLATFORM = "wayland;xcb";
+      QT_WAYLAND_DISABLE_WINDOWDECORATION = "1";
+    };
+  };
+}