fix(tmux): add spaces between sessionx startup commands

The The `&&` separator in `concatStringsSep` was missing spaces, causing the tmux sessionx startup command to be malformed and fail. This change adds the required spaces.

home/features/cli/tmux.nix

@@ -42,7 +42,7 @@ in
           set -g @sessionx-custom-paths-subdirectories true
           set -g @sessionx-custom-paths-subdirectories-depth 2
           set -g @sessionx-name-template '{-2}/{-1}'
-          set -g @sessionx-startup-command '${builtins.concatStringsSep "&&" [
+          set -g @sessionx-startup-command '${builtins.concatStringsSep " && " [
             "tmux new-window -n gemini -t {session}"
             "tmux new-window -n terminal -t {session}"
             "tmux rename-window -t {session}:1 editor"