build(flake): update nixpkgs to nixos-unstable

- Replace flake.nix nixpkgs URL with github:nixos/nixpkgs/nixos-unstable
- Update flake.lock to new locked rev, narHash and github type

No functional changes to scripts; resolves dependency refresh for Nix flakes.,

flake.lock

@@ -16,16 +16,18 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1768940263,
-        "narHash": "sha256-sJERJIYTKPFXkoz/gBaBtRKke82h4DkX3BBSsKbfbvI=",
-        "rev": "3ceaaa8bc963ced4d830e06ea2d0863b6490ff03",
-        "revCount": 906247,
-        "type": "tarball",
-        "url": "https://api.flakehub.com/f/pinned/NixOS/nixpkgs/0.2511.906247%2Brev-3ceaaa8bc963ced4d830e06ea2d0863b6490ff03/019be1ae-9947-752c-81ca-8b8670ae9892/source.tar.gz"
+        "lastModified": 1769170682,
+        "narHash": "sha256-oMmN1lVQU0F0W2k6OI3bgdzp2YOHWYUAw79qzDSjenU=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "c5296fdd05cfa2c187990dd909864da9658df755",
+        "type": "github"
       },
       "original": {
-        "type": "tarball",
-        "url": "https://flakehub.com/f/NixOS/nixpkgs/%2A.tar.gz"
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
       }
     },
     "root": {

flake.nix

@@ -2,7 +2,7 @@
   description = "Quickemu flake";
   inputs = {
     flake-schemas.url = "https://flakehub.com/f/DeterminateSystems/flake-schemas/*.tar.gz";
-    nixpkgs.url = "https://flakehub.com/f/NixOS/nixpkgs/*.tar.gz";
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
   };
 
   outputs =