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/config/src/tui_keymap.rs

@@ -239,6 +239,8 @@ pub struct TuiVimNormalKeymap {
     pub delete_char: Option<KeybindingsSpec>,
     /// Replace the character under the cursor (`r`).
     pub replace_char: Option<KeybindingsSpec>,
+    /// Repeat the last complete edit (`.`).
+    pub repeat_last_change: Option<KeybindingsSpec>,
     /// Delete character under cursor and enter insert mode (`s`).
     pub substitute_char: Option<KeybindingsSpec>,
     /// Delete from cursor to end of line (`D`).