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/home/overview.nix

@@ -0,0 +1,22 @@
+{lib, ...}: let
+  overviewSource = ./overview;
+in {
+  # Quickshell-overview is a Qt6 QML app for Hyprland workspace overview
+  # It shows all workspaces with live window previews, drag-and-drop support
+  # Toggled via: SUPER + TAB (bound in hyprland/binds.nix)
+  # Started via exec-once in hyprland/exec-once.nix
+
+  # Seed the Quickshell overview code into ~/.config/quickshell/overview
+  # Copy (not symlink) so QML module resolution works and users can edit files
+  home.activation.seedOverviewCode = lib.hm.dag.entryAfter ["writeBoundary"] ''
+    set -eu
+    DEST="$HOME/.config/quickshell/overview"
+    SRC="${overviewSource}"
+
+    if [ ! -d "$DEST" ]; then
+      mkdir -p "$HOME/.config/quickshell"
+      cp -R "$SRC" "$DEST"
+      chmod -R u+rwX "$DEST"
+    fi
+  '';
+}