agent_ui: Fix keyboard navigation in ACP elicitation forms (#64193)

Closes #61358

Address the keyboard-navigation portions. Image answers are
intentionally not included. ACP form responses support primitive values
rather than image attachments, and Claude Code's adapter treats the
"Other" answer as text. This PR therefore only partially addresses the
issue.

Release Notes:

- acp: Fixed submitting and navigating ACP elicitation forms with the
keyboard.

assets/keymaps/default-linux.json

@@ -379,6 +379,15 @@
       "enter": "editor::Newline",
     },
   },
+  {
+    "context": "Elicitation || (Elicitation > Editor)",
+    "use_key_equivalents": true,
+    "bindings": {
+      "enter": "menu::Confirm",
+      "tab": "menu::SelectNext",
+      "shift-tab": "menu::SelectPrevious",
+    },
+  },
   {
     "context": "ThreadHistory",
     "bindings": {

assets/keymaps/default-macos.json

@@ -414,6 +414,15 @@
       "enter": "editor::Newline",
     },
   },
+  {
+    "context": "Elicitation || (Elicitation > Editor)",
+    "use_key_equivalents": true,
+    "bindings": {
+      "enter": "menu::Confirm",
+      "tab": "menu::SelectNext",
+      "shift-tab": "menu::SelectPrevious",
+    },
+  },
   {
     "context": "ThreadHistory",
     "bindings": {

assets/keymaps/default-windows.json

@@ -382,6 +382,15 @@
       "enter": "editor::Newline",
     },
   },
+  {
+    "context": "Elicitation || (Elicitation > Editor)",
+    "use_key_equivalents": true,
+    "bindings": {
+      "enter": "menu::Confirm",
+      "tab": "menu::SelectNext",
+      "shift-tab": "menu::SelectPrevious",
+    },
+  },
   {
     "context": "ThreadHistory",
     "use_key_equivalents": true,