terra: desktop setup, flatpak, unstable packages, key management

- Hyprland workspace rules: start-communications.sh launches telegram +
  discord into special:communications; qbz/discord/telegram switched to
  flatpak (nix-flatpak, Flathub) — removes qbz and proton-pass-cli flake
  inputs
- proton-pass-cli and claude-code sourced from nixpkgs-unstable; unstable
  pkgs set threaded into home-manager via extraSpecialArgs
- GTK/libadwaita dark theme fixed: dconf color-scheme = prefer-dark written
  declaratively instead of a per-session gsettings call
- scripts/keys: store/restore SSH host keys and sops age keys via Proton
  Pass (ssh_host#<config> / age#<config> / age#admin naming)

services/desktop/desktop-apps.nix

@@ -35,10 +35,6 @@ in
     kdePackages.dolphin
     vivaldi
     rishot
-    # tome removed for now — private git+ssh flake input the installer can't
-    # fetch. The dev SDKs below stay (public, cached) for when it comes back.
-
-    # Tome development (Tome.App targets net10.0; ClientApp is Preact/Vite).
     dotnetCorePackages.sdk_10_0
     nodejs
   ];