Revert nixpkgs follows for comfy-ui, pi and nixos-hardware

Forcing these inputs to follow the root nixpkgs changed the ComfyUI
package's derivation hash, which invalidated the binary cache and queued
a 91-derivation rebuild (the full ComfyUI Python closure plus cudnn, nccl
and libnvshmem). Restore each input's own locked nixpkgs and the original
flake.lock, which matches the already-built, cached closure.

A dry-build now reports nothing to build. The single-nixpkgs cleanup is
not worth forcing multi-hour CUDA rebuilds.

flake.lock

@@ -51,9 +51,7 @@
     "comfy-ui": {
       "inputs": {
         "flake-parts": "flake-parts",
-        "nixpkgs": [
-          "nixpkgs"
-        ]
+        "nixpkgs": "nixpkgs"
       },
       "locked": {
         "lastModified": 1787851822,
@@ -188,9 +186,7 @@
     },
     "nixos-hardware": {
       "inputs": {
-        "nixpkgs": [
-          "nixpkgs"
-        ]
+        "nixpkgs": "nixpkgs_2"
       },
       "locked": {
         "lastModified": 1788044418,
@@ -209,16 +205,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1787962033,
-        "narHash": "sha256-u6z9VTZA4Kf3RkHQo9sQI7NI4Ei/uiU9vrMqOiwWP1Y=",
+        "lastModified": 1766902085,
+        "narHash": "sha256-coBu0ONtFzlwwVBzmjacUQwj3G+lybcZ1oeNSQkgC0M=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "c5c4a43b0e8056328ec4529f735cabdb8f1942bb",
+        "rev": "c0b0e0fddf73fd517c3471e546c0df87a42d53f4",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-26.05",
+        "ref": "nixos-unstable",
         "repo": "nixpkgs",
         "type": "github"
       }
@@ -254,13 +250,56 @@
         "type": "github"
       }
     },
+    "nixpkgs_2": {
+      "locked": {
+        "lastModified": 1767892417,
+        "narHash": "sha256-8bW3q88CEg2u4hSP66Vf4lpbLonHz7hqDNBMcCY7E9U=",
+        "rev": "3497aa5c9457a9d88d71fa93a4a8368816fbeeba",
+        "type": "tarball",
+        "url": "https://releases.nixos.org/nixos/unstable/nixos-26.05pre924538.3497aa5c9457/nixexprs.tar.xz"
+      },
+      "original": {
+        "type": "tarball",
+        "url": "https://channels.nixos.org/nixos-unstable/nixexprs.tar.xz"
+      }
+    },
+    "nixpkgs_3": {
+      "locked": {
+        "lastModified": 1787962033,
+        "narHash": "sha256-u6z9VTZA4Kf3RkHQo9sQI7NI4Ei/uiU9vrMqOiwWP1Y=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "c5c4a43b0e8056328ec4529f735cabdb8f1942bb",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-26.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_4": {
+      "locked": {
+        "lastModified": 1773646010,
+        "narHash": "sha256-iYrs97hS7p5u4lQzuNWzuALGIOdkPXvjz7bviiBjUu8=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "5b2c2d84341b2afb5647081c1386a80d7a8d8605",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
     "pi": {
       "inputs": {
         "bun2nix": "bun2nix",
         "jail-nix": "jail-nix",
-        "nixpkgs": [
-          "nixpkgs"
-        ],
+        "nixpkgs": "nixpkgs_4",
         "systems": "systems"
       },
       "locked": {
@@ -285,7 +324,7 @@
         "herdr": "herdr",
         "home-manager": "home-manager",
         "nixos-hardware": "nixos-hardware",
-        "nixpkgs": "nixpkgs",
+        "nixpkgs": "nixpkgs_3",
         "nixpkgs-unstable": "nixpkgs-unstable",
         "pi": "pi"
       }

flake.nix

@@ -4,10 +4,7 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-26.05";
     nixpkgs-unstable.url = "github:NixOS/nixpkgs/nixos-unstable";
-    nixos-hardware = {
-      url = "github:NixOS/nixos-hardware/master";
-      inputs.nixpkgs.follows = "nixpkgs";
-    };
+    nixos-hardware.url = "github:NixOS/nixos-hardware/master";
 
     home-manager = {
       url = "github:nix-community/home-manager/release-26.05";
@@ -26,7 +23,6 @@
 
     comfy-ui = {
       url = "github:utensils/comfyui-nix";
-      inputs.nixpkgs.follows = "nixpkgs";
     };
 
     herdr = {
@@ -36,7 +32,6 @@
 
     pi = {
       url = "github:lukasl-dev/pi.nix";
-      inputs.nixpkgs.follows = "nixpkgs";
     };
   };