fix(gui): exclude trailing Markdown emphasis delimiters from autolinked URLs (#197)

[justrach]

Problem

Bare URLs wrapped in Markdown emphasis (**url**, *url*, ~~url~~) captured the closing delimiters in the link target. On macOS, Cmd-hover/Cmd-click then underlined the trailing markers and tried to open an invalid destination such as http://localhost:3003**.

Markdown-rendered messages normally split strong spans first, but raw/plain-text paths (ChatInlineText / getInlineTextSegments) pass the markers straight into getChatLinkMatches.

Fix

The matcher now recognizes a contiguous Markdown delimiter immediately before a bare URL and removes only the matching closing delimiter from the candidate. This keeps Markdown syntax outside the clickable span without stripping valid URL characters from unwrapped links.

input	clickable target
**http://localhost:3003**	http://localhost:3003
*https://example.com*	https://example.com
~~https://example.com~~	https://example.com
https://example.com/path*	unchanged
https://example.com/~	unchanged
*https://example.com/path**	https://example.com/path*

The delimiter handling is URL-specific, so generic file/path candidate cleanup does not accidentally remove legitimate trailing markers.

Tests

• bun test: 157 passed, 0 failed.
• bunx eslint src/components/chat/utils/chatLinks.ts src/components/chat/utils/chatLinks.test.ts: passed.
• bunx tsc -b: passed.
• Added regressions for bold, italic, strikethrough, mixed delimiters, offsets, punctuation, multi-byte characters, and legitimate trailing * / ~ URL characters.

Repository-wide bun run lint remains blocked by eight pre-existing errors in unrelated GUI files. The Vite build also reaches the bundler but is blocked by the repository's existing missing esbuild dependency.

Closes #197

[justrach]

CI baseline note for reviewers:

• The branch-head workflow for d1056cf passed Zig, SDK, and Windows.
• The pull-request merge workflow passed all 231 Zig unit tests, then failed the JSON live-control integration test after 8/19 cases stopped receiving events.
• Rerunning reproduced that integration failure.
• Current main fails identically in run 29633443960: 231/231 Zig tests pass, then the same JSON-control test stops after 8/19.

This is an existing main CI failure and is unrelated to this GUI-only URL matcher/test diff. Local validation for the changed area is green: 157 Bun tests, targeted ESLint, and TypeScript project checking.