flake: add 'nixgl'

There's now a home-manager module for it, let's try it out.

flake.lock

@@ -173,6 +173,30 @@
         "type": "github"
       }
     },
+    "nixgl": {
+      "inputs": {
+        "flake-utils": [
+          "futils"
+        ],
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1752054764,
+        "narHash": "sha256-Ob/HuUhANoDs+nvYqyTKrkcPXf4ZgXoqMTQoCK0RFgQ=",
+        "owner": "nix-community",
+        "repo": "nixGL",
+        "rev": "a8e1ce7d49a149ed70df676785b07f63288f53c5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "ref": "main",
+        "repo": "nixGL",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1752644555,
@@ -221,6 +245,7 @@
         "futils": "futils",
         "git-hooks": "git-hooks",
         "home-manager": "home-manager",
+        "nixgl": "nixgl",
         "nixpkgs": "nixpkgs",
         "nur": "nur",
         "systems": "systems"