Hover popup: only first bare URL clickable, rest still unregistered

[JDonaghy]

Problem

#497 fix landed (PR #503) but only partially works. The first bare URL in the hover popup is clickable, but subsequent bare URLs are still not registered as click targets.

Observed

• First bare URL in hover content: clickable
• All other bare URLs: styled as links (correct color) but not clickable

Likely cause

The bare URL detection or link registration logic in src/core/markdown.rs or src/core/engine/panels.rs may be stopping after the first match per line/block, or there's an off-by-one in the span offset tracking that causes subsequent URLs to not get registered in extract_hover_links().

Files to investigate

• src/core/markdown.rs — render_markdown() bare URL scanner (added in #497: Hover popup: bare URLs styled as links but not registered as clickable #503)
• src/core/engine/panels.rs — extract_hover_links() LinkUrl handling (added in #497: Hover popup: bare URLs styled as links but not registered as clickable #503)
• src/core/engine/tests.rs — existing tests may only cover single-URL cases

Repro

1. Hover a Rust symbol with rich docs containing multiple bare URLs (e.g. Vec, HashMap)
2. Scroll to see multiple URLs in link color
3. Click first URL — works
4. Click any subsequent URL — no response

Related

• Hover popup: bare URLs styled as links but not registered as clickable #497 (original issue, closed by #497: Hover popup: bare URLs styled as links but not registered as clickable #503)
• PR #497: Hover popup: bare URLs styled as links but not registered as clickable #503 (the fix that partially works)