Comprehensive 16-point checklist covering every integration point
needed when adding a new messaging platform to the gateway. Built
from the Signal integration experience where 7 integration points
were initially missed.
Covers: adapter, config enum, factory, auth maps, session source,
prompt hints, toolsets, cron delivery, send_message tool, cronjob
tool schema, channel directory, status display, setup wizard,
redaction, documentation, and tests.
