Add WhatsApp Channel

Adds WhatsApp support via the native Baileys adapter — a direct WhatsApp Web connection, no Chat SDK bridge. NanoClaw doesn't ship channels in trunk — this skill copies the WhatsApp 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.

Number safety check (required)

Complete this check before running any install or authentication command. If the user already said they want to use their shared, personal, main, existing, or everyday WhatsApp number, treat it as a shared number and show the warning immediately. Do not ask the number-type question again.