Add Ventoy support and refactor wallpaper handling

Introduce a `ventoy.enable` option (default false) and import the new
`modules/core/ventoy.nix` in the core module list. All host
`system-modules.nix` files now disable Ventoy explicitly.

Make the boot wallpaper configurable by importing `stylixImage` from the
host’s `variables.nix` and using it in `modules/core/boot.nix`.

Update each host’s `variables.nix` to set a default wallpaper and keep
many alternatives commented out.

Remove the obsolete `restart.noctalia` and `screenshootin` scripts,
their Nix wrappers, and the related Hyprland keybinding.

Add a collection of new wallpaper files and delete the old, unused
images.

modules/home/scripts/default.nix

@@ -1,7 +1,5 @@
 {pkgs, ...}: {
   home.packages = [
     (import ./nvidia-offload.nix {inherit pkgs;})
-    (import ./restart.noctalia.nix {inherit pkgs;})
-    (import ./screenshootin.nix {inherit pkgs;})
   ];
 }

modules/home/scripts/restart.noctalia

@@ -1,54 +0,0 @@
-#!/usr/bin/env bash
-set -euo pipefail
-
-# Restart the Noctalia QuickShell session by terminating only the noctalia-shell
-# processes, avoiding any signals to unrelated process groups (e.g. Hyprland).
-
-log() { printf "[restart.noctalia] %s\n" "$*"; }
-
-list_target_pids() {
-  # Collect only PIDs whose command explicitly runs noctalia-shell
-  # - direct wrapper: ".../noctalia-shell"
-  # - quickshell/qs with "-c noctalia-shell"
-  ps -eo pid=,cmd= \
-    | ${GREP:-grep} -E "(^|/)(noctalia-shell)( |$)|(^| )((qs|quickshell))( | ).*-c( |=)?noctalia-shell( |$)" \
-    | awk '{print $1}'
-}
-
-terminate_targets() {
-  local pids left tries
-  mapfile -t pids < <(list_target_pids || true)
-
-  if ((${#pids[@]} > 0)); then
-    kill -TERM "${pids[@]}" 2>/dev/null || true
-  fi
-
-  # Wait up to ~3s for clean exit
-  for tries in {1..15}; do
-    mapfile -t left < <(list_target_pids || true)
-    ((${#left[@]} == 0)) && break
-    sleep 0.2
-  done
-
-  # Force kill leftovers only (do not touch anything else)
-  if ((${#left[@]} > 0)); then
-    kill -KILL "${left[@]}" 2>/dev/null || true
-  fi
-}
-
-start_noctalia() {
-  # Prefer the noctalia-shell wrapper to ensure proper env and runtime flags
-  if command -v noctalia-shell >/dev/null 2>&1; then
-    nohup setsid noctalia-shell >/dev/null 2>&1 &
-  elif command -v quickshell >/dev/null 2>&1; then
-    nohup setsid quickshell -c noctalia-shell >/dev/null 2>&1 &
-  elif command -v qs >/dev/null 2>&1; then
-    nohup setsid qs -c noctalia-shell >/dev/null 2>&1 &
-  else
-    echo "Error: noctalia-shell/quickshell/qs not found in PATH" >&2
-    exit 1
-  fi
-}
-
-terminate_targets
-start_noctalia

modules/home/scripts/restart.noctalia.nix

@@ -1,24 +0,0 @@
-{pkgs, ...}: let
-  binPath = pkgs.lib.makeBinPath [
-    pkgs.coreutils
-    pkgs.procps
-    pkgs.psmisc
-    pkgs.gnugrep
-    pkgs.findutils
-    pkgs.util-linux
-    pkgs.bash
-  ];
-  script = builtins.readFile ./restart.noctalia;
-in
-  pkgs.writeShellScriptBin "restart.noctalia" ''
-      set -euo pipefail
-      export PATH=${binPath}:$PATH
-
-      tmp_script=$(mktemp)
-      trap 'rm -f "$tmp_script"' EXIT
-      cat > "$tmp_script" <<'BASH_EOF'
-    ${script}
-    BASH_EOF
-      chmod +x "$tmp_script"
-      exec ${pkgs.bash}/bin/bash "$tmp_script" "$@"
-  ''

modules/home/scripts/screenshootin.nix

@@ -1,4 +0,0 @@
-{pkgs}:
-pkgs.writeShellScriptBin "screenshootin" ''
-  grim -g "$(slurp)" - | swappy -f -
-''