Add dot-repeat to Vim mode (#40521)

## What changed

- Bind `.` in Vim normal mode to repeat the last complete edit.
- Record semantic delete, change, replace, paste, and insert-mode actions so repeats preserve motions, text objects, inserted text, and editor actions across keymap changes.
- Expose `vim_normal.repeat_last_change` in the configurable keymap and keymap picker, including conflict handling for existing custom bindings.

## Testing

- Add coverage for repeating deletes, replacements, complete changes, pasted and literal text, insert-mode editor actions, custom bindings, unavailable motions, and cleared buffers.

GitOrigin-RevId: 3213df964811e7902377ff1d93641e59f4037914

codex-rs/core/config.schema.json

@@ -3801,6 +3801,7 @@
               "open_line_above": null,
               "open_line_below": null,
               "paste_after": null,
+              "repeat_last_change": null,
               "replace_char": null,
               "start_change_operator": null,
               "start_delete_operator": null,
@@ -4608,6 +4609,7 @@
             "open_line_above": null,
             "open_line_below": null,
             "paste_after": null,
+            "repeat_last_change": null,
             "replace_char": null,
             "start_change_operator": null,
             "start_delete_operator": null,
@@ -5016,6 +5018,14 @@
           ],
           "description": "Paste after cursor (`p`)."
         },
+        "repeat_last_change": {
+          "allOf": [
+            {
+              "$ref": "#/definitions/KeybindingsSpec"
+            }
+          ],
+          "description": "Repeat the last complete edit (`.`)."
+        },
         "replace_char": {
           "allOf": [
             {