feat(config): add down-arrow binding for silent pj invocation on empty prompt

dot_config/fish/functions/fish_user_key_bindings.fish

@@ -19,6 +19,11 @@ function fish_user_key_bindings
         bind -M $mode ctrl-p 'pj; commandline -f repaint'
         bind -M $mode ctrl-a 'omp; commandline -f repaint'
 
+        # Arrow keys: atuin owns up (bound from config.fish, survives the
+        # fish_vi_key_bindings reset above because that only erases presets),
+        # down runs pj — but only on an idle, empty prompt; see _pj_bind_down.
+        bind -M $mode down _pj_bind_down
+
         # ctrl-f: pick file(s) with television and open in nvim.
         bind -M $mode ctrl-f 'yy; commandline -f repaint'
         bind -M $mode ctrl-g 'lazygit; commandline -f repaint'