feat(ui): testbench markdown descriptions and DCR redirect URIs modal

[spelech]

Summary

This PR combines two UI/UX enhancements:

1. Test Bench Formatted Descriptions:

   • Strips redundant [server-name] prefix from tool and prompt descriptions.
   • Parses markdown paragraphs, unordered bullet lists (- , * ), ordered lists (1. ), inline code (code), bold (**), italic (*), and safe external links via zero-dependency <FormattedDescription /> component.
   • Enhances CSS typography with comfortable line height and monospace glassmorphic badges (UI-138).

2. DCR Redirect URIs Table Compacting & Detail Modal:

   • Replaces vertical multi-URI stacking in the Dynamic Client Registration (RFC 7591) table with a compact single-line view (first URI truncated with ellipsis + interactive +N more badge button).
   • Introduces <RedirectUrisModal /> displaying full-width monospace URIs, individual 1-click copy buttons, and a Copy All action (UI-139).

Tests & Verification

• All 44 frontend test suites passing (284 tests).
• Requirements catalog verified with zero drift (458 requirements across 1,051 proofs).