tech-debt(search): migrate dead Tailwind classes in dialog to Remarque CSS

[williamzujkowski]

Found during live chrome review (see #205).

Search.svelte uses Tailwind arbitrary-value classes throughout the search dialog but Tailwind is not installed. Classes never compile; only inline styles carry the dialog.

Scope: migrate remaining Tailwind classes to scoped CSS in the <style> block using Remarque tokens.

Trigger button already fixed in #205.