fix(tui): use OSC 8 hyperlinks for multiline link support

[simonklee]

Summary

• Use <a href> element to generate OSC 8 terminal hyperlinks for the Link component
• OSC 8 hyperlinks correctly span multiple wrapped lines in supporting terminals
• Keep onMouseUp handler as fallback for terminals without OSC 8 support

Problem

When authorization URLs wrap across multiple lines in the dialog, clicking on the wrapped portion doesn't open the URL (issue #6639).

Solution

Wrap the link text in an <a href> element which generates OSC 8 terminal escape sequences. These hyperlinks are handled natively by the terminal and work correctly across line wraps. The onMouseUp handler is preserved as a fallback.

Test plan

• Verified typecheck passes
• OSC 8 hyperlinks are supported by most modern terminals (iTerm2, Ghostty, Kitty, Windows Terminal, etc.)

Fixes #6639

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Duplicate Search Results

No duplicate PRs found.

The search returned only PR #6995 (the current PR) and one unrelated PR (#4791 about bash tool expansion). The specific focus on:

• OSC 8 hyperlinks
• Multiline link support in TUI
• Fixing issue [Bug] multiline file link does not work #6639

...appears to be unique to this PR. There are no other open PRs addressing the same terminal hyperlink functionality or the wrapped authorization URL problem.

Status: ✅ Safe to merge - no duplicates detected.