Sync leaderboard data from RouterArena

[yl231]

Automated update of src/data from RouterArena
(commit 78fb83a966fd99da589812e4efb2f3ab0b8971dd).

• routerMetrics/leaderboard.json — headline metrics (sourced from README)
• routerMetrics/category_scores.json — per-difficulty breakdown
• flip_labels/* — per-query robustness flips

Generated by scripts/website/build_site_data.py.

[YangY-Z]

Hi @yl231, I noticed PR #45 is currently blocked only by the pre-commit check.

I reproduced the failure locally and it looks like end-of-file-fixer only needs to add trailing newlines to the updated JSON files, including:

• src/data/routerMetrics/leaderboard.json
• src/data/routerMetrics/category_scores.json
• src/data/flip_labels/flip_labels_agentforge.json
• other updated flip_labels_*.json files

The fix may be just:

pre-commit run --all-files
git add src/data
git commit -m "Fix pre-commit formatting"
git push

Since this PR has maintainer_can_modify: false, could the PR author push this formatting fix?