terra: add proton-pass-cli via flake input

Not in nixpkgs; packaged by github:tomsch/proton-pass-cli-nix. Used by
./scripts/deploy to autofill sudo/ssh passwords from the "HomeLab" vault.

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

hosts/terra/configuration.nix

@@ -1,4 +1,4 @@
-{ config, pkgs, lib, ... }:
+{ config, pkgs, lib, inputs, ... }:
 
 # terra — Ryzen 9 5900X / Radeon RX 6800 XT desktop (MSI MS-7A32). Replaces
 # CachyOS on the OS SSD (Kingston SA400, sdb). Dev-data disks (sdc ext4
@@ -18,6 +18,11 @@
 
   networking.hostName = "terra";
 
+  # Proton Pass CLI — not in nixpkgs; ./scripts/deploy uses it to autofill
+  # sudo/ssh passwords from the "HomeLab" vault. Packaged by the
+  # proton-pass-cli flake input (github:tomsch/proton-pass-cli-nix).
+  environment.systemPackages = [ inputs.proton-pass-cli.packages.${pkgs.system}.default ];
+
   # ---- home-manager (user-level config for darman) ----
   home-manager.useGlobalPkgs = true;
   home-manager.useUserPackages = true;