feat(config): add scratch terminal binding and window rule, remove pj function

dot_config/fish/functions/_pj_bind_down.fish

@@ -1,18 +1,21 @@
-function _pj_bind_down --description "down arrow: pj on an idle empty prompt, else the preset down-or-search"
+function _pj_bind_down --description "down arrow: pj on an idle empty prompt, else fish's down-or-search"
     # Mirror of atuin's up binding (atuin owns up, this owns down). Everything
     # that legitimately needs the arrow keys keeps them:
     #   - non-empty buffer  → multiline cursor movement / forward history search
     #   - paging mode       → tab-completion pager navigation (tab on an empty
     #                         line opens the pager with an empty buffer)
     #   - search mode       → history-search navigation
+    # down-or-search is fish's own input function, called as a command exactly
+    # the way atuin's _atuin_bind_up calls up-or-search.
     set -l buf (commandline | string collect)
     if test -n "$buf"; or commandline --paging-mode; or commandline --search-mode
-        commandline -f down-or-search
+        down-or-search
         return
     end
 
-    # PJ_QUIET keeps pj silent when the tree has no package.json, so down is a
-    # no-op outside JS projects instead of printing an error on every press.
+    # pj is ~/.local/bin/pj (shared with the zsh ctrl-p binding). PJ_QUIET
+    # keeps it silent when the tree has no task source at all, so down is a
+    # no-op outside projects instead of printing an error on every press.
     PJ_QUIET=1 pj
     commandline -f repaint
 end