Reconcile verified agent pull request merges

[ranade-oss]

Summary

Add a scheduled and manual reconciliation pass for open eligible agent/** pull requests that already have a successful exact-head Baseline.

Behavior

• runs every five minutes and on manual dispatch;
• finds trusted same-repository agent PRs and marked upstream-sync bot PRs;
• requires a successful Baseline for the current exact head;
• rechecks draft state, head SHA, requested changes, unresolved review threads, and GitHub mergeability;
• squash-merges only when every existing gate passes;
• leaves blocked PRs open for a later reconciliation pass.

Safety

This closes the one-shot timing gap without weakening any merge condition. High-risk drafts remain excluded, stale heads cannot merge, and failed or absent Baselines remain ineligible.