feat: remplacer light par acpilight/xbacklight, ajouter ddcutil pour écrans externes

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages.nix

@@ -1,10 +1,24 @@
 { pkgs, lib, ... }:
 
+let
+  pythonOverlay = final: prev: {
+    python313 = prev.python313.override {
+      packageOverrides = pyself: pysuper: {
+        picosvg = pysuper.picosvg.overrideAttrs (_: {
+          doCheck = false;
+        });
+      };
+    };
+    python313Packages = final.python313.pkgs;
+  };
+in
 let
   atomicptr = import (fetchTarball
     "https://github.com/atomicptr/nix/archive/refs/heads/master.tar.gz") { };
   rtk = pkgs.callPackage ./pkgs/rtk.nix { };
 in {
+  nixpkgs.overlays = [ pythonOverlay ];
+
   nixpkgs.config.allowUnfreePredicate = pkg:
     builtins.elem (lib.getName pkg) [
       "1password"
@@ -104,7 +118,7 @@ in {
     mattermost-desktop
     signal-desktop
     libreoffice
-    freemind
+    ddcutil
     filezilla
     vokoscreen-ng
     ffmpeg
@@ -179,6 +193,7 @@ in {
     audacity
     freeplane
     calibre
+    retext
     gparted
     ticktick
     agate