Track nixpkgs nixos-26.05 (stable) instead of nixos-25.05

Verified via nix flake check -L: package builds against PHP 8.4.26
with the existing vendorHash still valid, and both vm-test/vm-test-caddy
boot, migrate, and log in successfully.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

flake.lock

@@ -2,16 +2,16 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1767313136,
-        "narHash": "sha256-16KkgfdYqjaeRGBaYsNrhPRRENs0qzkQVUooNHtoy2w=",
+        "lastModified": 1791031588,
+        "narHash": "sha256-/FGDr01siZ8txrVzkOz6CYjiz0XR27JuVJP+aWchi4s=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "ac62194c3917d5f474c1a844b6fd6da2db95077d",
+        "rev": "825e2028c29b702a4a5f085f08095d12099784f2",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-25.05",
+        "ref": "nixos-26.05",
         "repo": "nixpkgs",
         "type": "github"
       }

flake.nix

@@ -1,7 +1,7 @@
 {
   description = "HortusFox — self-hosted plant manager, from source";
 
-  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05";
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-26.05";
   inputs.utils.url = "github:numtide/flake-utils";
   inputs.systems.url = "github:nix-systems/default";