Consolidate minimal-buildtype hosts onto a single nix-minimal identity

linode-minimal, proxmox-minimal, and lxc-minimal now all share
hosts/nix-minimal/host.nix instead of three separate per-platform
host files with different hostnames — every minimal-buildtype host is
named nix-minimal regardless of which platform it runs on.

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

flake.nix

@@ -62,9 +62,9 @@
       # variant (PXE/DHCP/TFTP need LAN L2 adjacency, which a Linode VPS
       # doesn't have).
       generatedTargets = {
-        linode-minimal = mkTarget { platform = "linode"; buildType = "minimal"; hostPath = ./hosts/linode-minimal/host.nix; };
+        linode-minimal = mkTarget { platform = "linode"; buildType = "minimal"; hostPath = ./hosts/nix-minimal/host.nix; };
-        proxmox-minimal = mkTarget { platform = "proxmox"; buildType = "minimal"; hostPath = ./hosts/proxmox-minimal/host.nix; };
+        proxmox-minimal = mkTarget { platform = "proxmox"; buildType = "minimal"; hostPath = ./hosts/nix-minimal/host.nix; };
-        lxc-minimal = mkTarget { platform = "lxc"; buildType = "minimal"; hostPath = ./hosts/lxc-minimal/host.nix; };
+        lxc-minimal = mkTarget { platform = "lxc"; buildType = "minimal"; hostPath = ./hosts/nix-minimal/host.nix; };
 
         linode-nix-cache = mkTarget { platform = "linode"; buildType = "nix-cache"; hostPath = ./hosts/nix-cache/host.nix; };
         proxmox-nix-cache = mkTarget { platform = "proxmox"; buildType = "nix-cache"; hostPath = ./hosts/nix-cache/host.nix; };

hosts/linode-minimal/host.nix

@@ -1,9 +0,0 @@
-{ ... }:
-
-{
-  networking.hostName = "linode-minimal";
-
-  # Preserved from the pre-refactor `linode-minimal` target — stateVersion
-  # must never be bumped on an already-installed machine.
-  system.stateVersion = "26.05";
-}

hosts/lxc-minimal/host.nix

@@ -1,9 +0,0 @@
-{ ... }:
-
-{
-  networking.hostName = "lxc-minimal";
-
-  # No pre-existing deployed machine to preserve — pin explicitly to the
-  # current release rather than let it silently default.
-  system.stateVersion = "26.05";
-}

variables.nix

@@ -10,6 +10,7 @@
   # Cross-host references (LAN hostnames/users other hosts reach over the network)
   nixCacheHost = "nix-cache"; # substituter/remote-builder hostname
   nfsServerHost = "server"; # NFS export source hostname
+
   remoteBuilderUser = "nixremote"; # remote builder SSH user
 
   # System