next.js

68bf1416 - address self-review PR comments: split CI bundler coverage, improve AGENTS.md accuracy, clean up benchmark config

address self-review PR comments: split CI bundler coverage, improve AGENTS.md accuracy, clean up benchmark config - Dev CI job uses turbopack (default), prod CI job uses webpack, covering both bundler paths - Soften HEADLESS instruction, add flaky test detection note, clarify define-env.ts scope - Scope vendored React docs to App Router, update CI env var documentation - Remove serverMinification from benchmark configs to test with defaults