Add Prism Launcher support and update flake lock

- Add a new home.prismlauncher module with an enable option and a
  custom package override.
- Enable Prism Launcher for the Garand‑Desktop host and remove the
  previous disabled flag.
- Add the user to the “video” group.
- Remove prismlauncher from the core packages list.
- Bump revisions and hashes for several inputs in flake.lock.
- Fix a trailing newline in the helium AppImage definition.

modules/home/prismlauncher.nix

@@ -0,0 +1,28 @@
+{
+  pkgs,
+  inputs,
+  system,
+  lib,
+  config,
+  ...
+}: let
+  prismlauncher-cracked-fixed = inputs.prismlauncher-cracked.packages.${system}.default.override {
+    prismlauncher-unwrapped =
+      (inputs.prismlauncher-cracked.packages.${system}.prismlauncher-unwrapped.override {
+        extra-cmake-modules = pkgs.kdePackages.extra-cmake-modules;
+      }).overrideAttrs (oldAttrs: {
+        nativeBuildInputs =
+          (oldAttrs.nativeBuildInputs or [])
+          ++ [
+            pkgs.pkg-config
+          ];
+      });
+  };
+in {
+  options.prismlauncher.enable = lib.mkEnableOption "Enable Prism Launcher";
+
+  config.programs.prismlauncher = lib.mkIf config.prismlauncher.enable {
+    enable = true;
+    package = prismlauncher-cracked-fixed;
+  };
+}