ci: dispatch EvalOpsBot review requests immediately

[haasonsaas]

Summary

• Add the standard EvalOpsBot pull_request.review_requested trigger.
• Dispatch the central deep PR lens workflow immediately when EvalOpsBot is requested.
• Mark evalops-pr-lens/meta-review pending on the PR head SHA to avoid scheduled fallback duplication.

Test Plan

• actionlint .github/workflows/evalopsbot-review-request.yml in evalops/deploy
• End-to-end validated on evalops/deploy#3822: source workflow dispatched central repository_dispatch review and EvalOpsBot posted a high-confidence finding.