Add WhatsApp Cloud API Channel

Connect NanoClaw to WhatsApp via the official Meta WhatsApp Business Cloud API. NanoClaw doesn't ship channels in trunk — this skill copies the WhatsApp Cloud adapter in from the channels branch.

The mechanical steps under Apply carry nc: directive fences: an agent reads the prose and applies them, and a parser can apply them deterministically from the same document. Every directive is idempotent, so the whole skill is safe to re-run; anything a parser can't apply falls back to the prose beside it.

Apply

1. Copy the adapter

Fetch the channels branch and copy the WhatsApp Cloud adapter into src/channels/ (overwrite — the branch is canonical):