feat(leaderboard): add notte entry, refine methodology notes, and harden external link policy

[nibzard]

This PR consolidates the last 11 commits and updates leaderboard content, methodology transparency, and link safety behavior.

What changed

• Added Notte to the leaderboard and aligned its metadata/methodology context.
• Added/updated dataset typing/labels to include webvoyager30 and wired related display behavior.
• Removed an old rows from leaderboard output (Convergence acquired, Kura 404, etc.) and adjusted nearby ordering/labels.
• Added FAQ methodology enhancements and a new FAQ items.
• Added a repository issue template for submitting WebVoyager leaderboard updates.
• Standardized outbound link behavior for target="_blank" links with explicit rel handling.
• Added a reusable rel policy in the leaderboard table for safety (noopener noreferrer, with nofollow for non-Steel domains).

[vercel]

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