Introduce `lhyper` and `rhyper` keys

Would it be possible to support an `lhyper` (`lshift + lcmd + lalt + lctrl`) and `rhyper` (`rshift + rcmd + ralt + rctrl`) key. This would make it easier to define key bindings like `rhyper + lshift - return`.

The issue names no files, tests, or entry points. Start by locating where key names are parsed and where modifier combinations are registered, then trace the existing left- and right-sided modifier handling. Done means both lhyper and rhyper are accepted in bindings such as `rhyper + lshift - return` and the behavior is covered by the project's available checks.

Written by the indexing model from the issue text.