Update dependencies and add Helium appimage

- Refresh many lock entries in flake.lock with new revisions and hashes.
- Enable the Helium appimage in default, desktop, and laptop host
  configs; add
  comment sections for web browsers and disable Fluxer by default.
- Rename the affinity option description from “Steam” to “Affinity”.
- Refactor appimage handling: introduce a generic mkAppImagePackage
  helper,
  import individual packages, and expose per‑package enable options.
- Update fluxer.nix to use a configurable icon size and adjust install
  paths.
- Bump Helium to version 0.12.3.1, update its hash, and make its icon
  size
  configurable.
- Adjust Hyprland settings: comment out the split‑layout bind, set
  configType = "hyprlang", enable Xwayland early, move vfr to the debug
  section, and comment out dwindle pseudotile.

modules/core/packages/appimages/default.nix

@@ -1,6 +1,20 @@
-{pkgs, ...}: let
-  fluxer = pkgs.callPackage ./fluxer.nix {};
-  helium = pkgs.callPackage ./helium.nix {};
+{
+  pkgs,
+  lib,
+  config,
+  ...
+}: let
+  mkAppImagePackage = name: pkg: {
+    options.packages.appImages.${name}.enable = lib.mkEnableOption name;
+
+    config.environment.systemPackages =
+      lib.mkIf config.packages.appImages.${name}.enable [pkg];
+  };
+
+  appImagePackages = {
+    fluxer = pkgs.callPackage ./fluxer.nix {};
+    helium = pkgs.callPackage ./helium.nix {};
+  };
 in {
-  environment.systemPackages = [fluxer helium];
+  imports = builtins.attrValues (builtins.mapAttrs mkAppImagePackage appImagePackages);
 }