Add IonWarp to Agents.md

When your repo connects, IonWarp opens ONE short PR — chore: add IonWarp to Agents.md — appending a single IonWarp section to your AGENTS.md / CLAUDE.md. It turns on two things for every coding agent that reads those files:

• PR Autofix — after pushing to a PR, the agent waits for the IonWarp / Review check (or its deadline), triages each finding with the review summary as context, fixes what's real in one fixpack commit, and replies wontfix: <reason> to anything that isn't (which re-computes the check without a new review run). A slow or failed review never blocks — an open blocker is the only state that can gate a merge, and only if you mark the check required in GitHub.
• Session Analytics — the agent appends a small collapsed 🛸 IonWarp Session Analytics block to its PR descriptions: planning vs coding vs CI time, which test surfaces ran, and the #1 thing slowing it down.

The PR is docs-only, idempotent (re-runs patch the <!-- ionwarp:agents-md v1 --> section in place), and zero lock-in — delete the section any time. IonWarp reviews the enablement PR itself, so merging it is also your first review.

The checklist step goes green when the PR merges — the merge webhook writes a durable enablement record; nothing scans your repo per render. Pressing the step re-checks the marker and re-opens the PR only if it is absent (already_open short-circuits to the existing PR).