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)

hosts/terra/secrets.nix

@@ -12,4 +12,13 @@
 
   sops.secrets.darman_password.neededForUsers = true;
   users.users.darman.hashedPasswordFile = config.sops.secrets.darman_password.path;
+
+  # Credentials file for the //jupiter/data cifs mount (see configuration.nix).
+  # samba_password mirrors jupiter's own samba_password secret (services/network/samba.nix) —
+  # same value, just also encrypted to terra so it can authenticate as the same smb user.
+  sops.secrets.samba_password = { };
+  sops.templates."jupiter-smb.credentials".content = ''
+    username=darman
+    password=${config.sops.placeholder.samba_password}
+  '';
 }