Keep Markdown links intact

[rizen]

What this improves

Links written with a label and destination now stay as one valid link. Pasted web addresses outside a link still receive the usual helpful formatting.

This prevents the broken, nested link shown in plainblack/TGC#2771.

Checks

• Added the exact example from the ticket; it failed before the change and now passes.
• Confirmed that an ordinary pasted address is still formatted normally.
• Saved the example on a local game and checked the public game page through the normal site address.

Resolves plainblack/TGC#2771