Closes #47251

Fix dot (`.`) repeat not correctly repeating the last change after
replaying a macro (`@register`)
([#47251](https://github.com/zed-industries/zed/issues/47251))

When replaying a macro that contains text insertions,
`replay_insert_event` calls `handle_input` directly and never emits
`InputHandled`, so the `observe_insertion` subscription never fires.
This left the dot register stale — `.` after `@register` would repeat an
earlier change instead of the last one made by the macro.

Fix by calling `observe_insertion` explicitly in the
`ReplayableAction::Insertion` branch of `Replayer::next`.

Release Notes:

- Fixed dot (`.`) repeat not repeating the last change made by a macro
(`@register`).

---------

Co-authored-by: Smit Barmase <heysmitbarmase@gmail.com>