feat(config)!: fixed conflicting keybinds, allow remap (#13)

The new default will now use <C-y> to close the codex window, remappable
by the user. Other vim standard methods have many conflicts with the
codex app

feat(config)!: support model option and improved UI behavior (#8)

* chore(ci): removed old branch ref

* feat(config): added ability to define model and fixed borders
  - `model` opt is now passed to the `-m` flag of the Codex CLI
  - Single border style no longer duplicates "rounded"

* chore(tests): moved files to avoid running full Plenary suite

* chore(readme): updated README.md with new config documentation

* fix(ui)!: resolved multiple buffer open/close issues
  - BREAKING CHANGE: Buffer toggle is now <q> instead of <Esc>
    This avoids conflict with the Codex CLI's newer interrupt sequence (<Esc><Esc>)
  - Buffer now backgrounds smoothly with no delay

* feat(tests): added model option tests

Update README.md

Initial release