fix(markdown): hide URL suffix for concealed links

[brendandebeasi]

Summary

• Remove redundant (url) suffix from concealed markdown links — the link text is already an OSC 8 hyperlink (Cmd/Ctrl+click), so displaying the raw URL is unnecessary
• Update two existing tests to match the new concealed link output

Context

When conceal is enabled, markdown links [text](url) render as text (https://...). Since the link text already carries the linkHref for OSC 8 terminal hyperlinks, the parenthesized URL is redundant visual noise. This change makes concealed links render as just text — clickable via Cmd/Ctrl+click in supporting terminals.

The non-concealed (conceal=false) path is unchanged and still shows the full [text](url) syntax.

[AnatoleLucet]

maybe this could be an option instead of the default?

for instance a new concealUrl: boolean options similar to concealCode: boolean:

• concealUrl: true -> <label>
• concealUrl: false -> <label> (<url>)

would still allow links to work on terminals that don't support OSC8 like today when false, and it wouldn't be a breaking change either :)