terra: cosmic portals, jupiter smb mount, tea CLI, launcher/theme polish

- swap gtk portal/apps for cosmic (xdg-desktop-portal-cosmic, cosmic-files,
  cosmic-settings) and drop dolphin/protonplus/bambu-studio (bambu-studio
  moved to flatpak alongside the other comms/gaming flatpaks)
- mount jupiter's samba share at /mnt/jupiter (automount, credentials from
  the same samba_password secret jupiter itself uses)
- add tea (gitea's remote API CLI) for talking to git.mgaction.town from
  terra without SSHing into jupiter
- new dark icon themes (Amy, Azure Glassy, Slot Beauty) vendored from
  gnome-look.org tarballs, packaged since pling download links expire
- rishot: fix Qt5Compat.GraphicalEffects QML import (was missing qt6.qt5compat
  on QML_IMPORT_PATH, so quickshell failed at config-load)
- launcher widgets: stop LauncherConsole/LauncherDock from reserving
  compositor space (ExclusionMode.Ignore, they're overlays not real docks);
  bump LauncherCorner app icon size 28->34
- comms script: launch telegram/discord via flatpak, not native binaries
- nix-ld + boot.binfmt aarch64 emulation (for building/flashing mercury
  from terra)

services/desktop/desktop-apps.nix

@@ -24,16 +24,20 @@ in
     enable = true;
     remotePlay.openFirewall = true;
     dedicatedServer.openFirewall = false;
+    gamescopeSession.enable = true;
+    extraCompatPackages = [ pkgs.proton-ge-bin ];
   };
   hardware.graphics.enable32Bit = true;
 
   environment.systemPackages = with pkgs; [
     alacritty
     zed-editor
-    protonplus
     gitkraken
     jetbrains-toolbox
-    kdePackages.dolphin
+    cosmic-settings-daemon
+    cosmic-settings
+    cosmic-icons
+    cosmic-files
     vivaldi
     rishot
     jq