fix(search): allow scrolling through search results

The results container never had a bounded height, so it grew to fit
all matches instead of scrolling — searches with many matches (e.g.
"code quality analysis" → 83 docs) only showed the first ~2.5 results
with no way to scroll further, and the overflow was silently clipped.

Bound .md-search__output to the dialog's available height and let it
own the scroll, instead of relying on an unbounded scrollwrap that
only worked by accident on narrow phone viewports via a media query.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: claudiacodacy