docs(2): Q5.1 — enroll-recipe.md §2.4 non-HTTP/multi-service/host-dependent recipes + mumble/mailu examples
Documents the Phase-2 Q4 patterns proven this session: EXTRA_ENV callable, READY_PROBE (HTTP+TCP),
CHAOS_BASE_DEPLOY, recipe_checkout -f, install_steps overlay-drop; non-HTTP protocol tests (mumble
host-ports + _mumble_proto), in-container functional tests (mailu flask/sendmail/doveadm under
TLS_FLAVOR=notls), and P4-N/A when a recipe ships no backupbot label. Worked-example pointers to
tests/mumble + tests/mailu.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>