Until now every keybinding config field was a plain string. That meant a user
couldn't ask for two keys to invoke a command — the config silently accepted
only one form.
Convert every string-typed field across all 13 KeybindingXxxConfig structs to
Keybinding so the union type extends to every command. Defaults wrap their
single-key value in Keybinding{...} so the generated Config.md still renders one
scalar key per binding.
The alt fields keep their separate Binding registrations for now: this commit
does not yet introduce the merge mechanism that folds them into the main field —
that comes in a follow-up. Consumers previously calling opts.GetKeys on a string
field now call opts.GetKeys on the Keybinding, or take .String() / Keys[0] where
a single value is needed.
Adds a Keybinding.String helper for rendering, schema-generator work that
inlines the Keybinding union into each consuming property, and a unit test
covering the user-facing scalar/sequence YAML forms for quit.
It seems useful to have the flexibility to remap "enter" in confirmations to
"y", but keep "enter" for menus and suggestions (even though we sometimes use
menus as confirmations, but it's still good to give users the choice).
So far, confirmations and prompts were handled by the same view, context, and
controller, with a bunch of conditional code based on whether the view is
editable. This was more or less ok so far, since it does save a little bit of
code duplication; however, now we need separate views, because we don't have
dynamic keybindings, but we want to map "confirm" to different keys in
confirmations (the "universal.confirm" user config) and prompts (hard-coded to
enter, because it doesn't make sense to customize it there).
It also allows us to get rid of the conditional code, which is a nice benefit;
and the code duplication is actually not *that* bad.
For custom commands it is useful to select an earlier command and have it copied
to the prompt for further editing. This can be done by hitting 'e' now.
For other types of suggestion panels we don't enable this behavior, as you can't
create arbitrary new items there that don't already exist as a suggestion.
In the custom commands panel you can now tab to the suggestions and hit 'd' to
delete items from there. Useful if you mistyped a command and don't want it to
appear in your history any more.