feat(hosts): make config multi-host and add vps host

Parametrize networking, users, and containers modules under
myNetworking/myUsers/myContainers so both hosts share the same logic
instead of duplicating it, and split desktop/server module imports
into modules/profiles/. Adds hosts/vps (not installed yet, hardware
config and bootloader device are placeholders) to run Traefik,
Headscale, Headplane, and Gitea via a combined Docker Compose stack.

Wires up agenix for secrets and migrates miku-homelab's WireGuard
private key off a plain filesystem path into an encrypted
secrets/miku-homelab-wg.age. The vps side of that tunnel still needs
its own key generated and encrypted after install.

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

hosts/vps/hardware-configuration.nix

@@ -0,0 +1,23 @@
+{ lib, ... }:
+
+# PLACEHOLDER: this host has not been installed yet. Replace this whole file
+# with the real hardware-configuration.nix generated by `nixos-generate-config`
+# during the actual installation (it will pick up the real disk UUIDs,
+# filesystem types, and kernel modules for the VPS provider's image).
+{
+  imports = [ ];
+
+  boot.initrd.availableKernelModules = [ "ata_piix" "uhci_hcd" "virtio_pci" "virtio_scsi" "sd_mod" "sr_mod" ];
+  boot.initrd.kernelModules = [ ];
+  boot.kernelModules = [ ];
+  boot.extraModulePackages = [ ];
+
+  fileSystems."/" = {
+    device = "/dev/disk/by-uuid/00000000-0000-0000-0000-000000000000";
+    fsType = "ext4";
+  };
+
+  swapDevices = [ ];
+
+  nixpkgs.hostPlatform = lib.mkDefault "x86_64-linux";
+}