ci: add plasma-bigscreen to cached packages

Add plasma-bigscreen to CI cache and expose it in flake packages.
The package is built from upstream master (not yet in nixpkgs).

.gitea/workflows/ci.yml

@@ -52,6 +52,7 @@ jobs:
             qt-pinned-jellyfin-media-player
             qt-pinned-stremio
             nix-deck-kernel
+            plasma-bigscreen
           )
 
           FAILED=()

flake.nix

@@ -285,6 +285,8 @@
           "custom-opencode" = pkgs.custom.opencode;
           "qt-pinned-jellyfin-media-player" = pkgsQt.jellyfin-media-player;
           "qt-pinned-stremio" = pkgsQt.stremio;
+          # Plasma Bigscreen — not yet in nixpkgs, built from upstream
+          "plasma-bigscreen" = pkgs.kdePackages.callPackage ./roles/plasma-bigscreen/package.nix { };
         }
         // (
           if system == "x86_64-linux" then