feat: add NixOS Playwright support with system Chrome via flake devShell

flake.nix

@@ -11,7 +11,7 @@
   };
 
   outputs =
-    inputs@{ flake-parts, ... }:
+    inputs@{ flake-parts, nixpkgs, ... }:
     flake-parts.lib.mkFlake { inherit inputs; } {
       systems = [
         "x86_64-linux"
@@ -25,8 +25,15 @@
       ];
 
       perSystem =
-        { pkgs, ... }:
+        { system, pkgs, ... }:
         {
+          _module.args = {
+            pkgs = import nixpkgs {
+              inherit system;
+              config.allowUnfree = true;
+            };
+          };
+
           treefmt = {
             projectRootFile = "flake.nix";
             programs = {
@@ -41,10 +48,19 @@
               uv
               ruff
               pyright
+              google-chrome
             ];
 
             shellHook = ''
-              export UV_PYTHON_PREFERENCE=only-system
+              export UV_PYTHON_PREFERENCE=managed
+
+              # Set Playwright browser path (prefer system Chrome, fallback to nixpkg)
+              if [ -f /run/current-system/sw/bin/google-chrome ]; then
+                export PLAYWRIGHT_CHROMIUM_EXECUTABLE_PATH=/run/current-system/sw/bin/google-chrome
+              else
+                export PLAYWRIGHT_CHROMIUM_EXECUTABLE_PATH=${pkgs.google-chrome}/bin/google-chrome
+              fi
+              export PLAYWRIGHT_SKIP_VALIDATE_HOST_REQUIREMENTS=true
             '';
           };
         };