Add IonWarp to Agents.md

IonWarp reads your code and never writes to your repository — the GitHub App holds Contents: read-only. So the IonWarp section for your AGENTS.md / CLAUDE.md is a hand-off, not a PR from a bot:

• One click on your own PR. When a PR you open touches AGENTS.md or CLAUDE.md and the file has no IonWarp section yet, the review posts a single inline suggested change appending the section. Press Commit suggestion and GitHub commits it under your identity.
• The Agents.md panel. Project → Settings → Agents.md shows the exact section, a git apply patch against each file you have, and the one-line instruction for your coding agent ("append this section to AGENTS.md and/or CLAUDE.md — whichever exists — and open a PR").
• One hand-off comment per project. The first reviewed PR on a repo without the section carries one comment pointing at the panel. Never a second one.

The section 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 section is bounded by <!-- ionwarp:agents-md v3 --> … <!-- ionwarp:agents-md:end -->, idempotent (a newer version replaces the older one in place), and zero lock-in — delete it any time.

The checklist step goes green once the section is on your default branch — seen when a PR that carries it merges (the merge webhook writes a durable record) or when you open the Agents.md panel after a direct push; nothing scans your repo per render.