docs(evaluation): add Agent as Judge type to eval-types page

[SuhaniNagpal7]

Summary

• Add Agent as Judge section so the page covers all three canonical eval types (llm / code / agent) from eval_list.py.
• Expand Deterministic example table (format, substring, length, link, regex) and add Fuzzy Match + Ground Truth Match to Statistical Metric.
• Add Canonical type and Tools / KB columns to the quick-reference table.

Test plan

• Render docs site locally and verify the new section
• Confirm internal links resolve
• Spot-check sidebar and TOC for the new heading

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