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)

dotfiles/quickshell/open_launcher.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+
+hyprctl dispatch 'hl.dsp.global ("quickshell:launcher7")'

dotfiles/scripts/start-communications.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+# Start both comms apps; Hyprland window rules move them to special:communications.
+telegram-desktop &
+discord &