ACP follow (#34235)

Closes #ISSUE

Release Notes:

- N/A

---------

Co-authored-by: Agus Zubiaga <agus@zed.dev>
Co-authored-by: Anthony Eid <hello@anthonyeid.me>
Co-authored-by: Ben Brandt <benjamin.j.brandt@gmail.com>

assets/keymaps/default-linux.json

@@ -320,7 +320,8 @@
     "bindings": {
       "enter": "agent::Chat",
       "up": "agent::PreviousHistoryMessage",
-      "down": "agent::NextHistoryMessage"
+      "down": "agent::NextHistoryMessage",
+      "shift-ctrl-r": "agent::OpenAgentDiff"
     }
   },
   {