fix: nix-deck infinite recursion + add custom-qmd to CI

- Add specialArgs to nix-deck (was missing nixpkgs-unstable, causing
  infinite recursion when roles/local-inference evaluated it)
- Move local-inference import out of roles/default.nix: its module-level
  disabledModules/imports conflict with nix-deck's unstable-based nixpkgs
- Import local-inference directly in zix790prors (the only machine that
  enables it)
- Add custom-qmd and custom-opencode to CI build-and-cache packages

.gitea/workflows/ci.yml

@@ -48,6 +48,8 @@ jobs:
             custom-mcrcon-rbw
             custom-tea-rbw
             custom-rclone-torbox-setup
+            custom-opencode
+            custom-qmd
             custom-nextcloud-talk-desktop
             qt-pinned-jellyfin-media-player
             qt-pinned-stremio