fix(search): allow scrolling through search results (#2712)

* 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>

* fix(search): retarget scrollbar and focus styles to scroll container

Scrolling now happens on .md-search__output, so the custom scrollbar
and keyboard-focus outline need to target that element instead of the
old .md-search__scrollwrap, which no longer scrolls.

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

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Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

Author: claudiacodacy