Sync customer touches from drip-cli

Push a batch of communication touches (iMessage / Slack / Gmail / LinkedIn / calendar / GitHub) to Drip. Body is truncated server-side to 200 chars; full message contents should never be sent. Each touch is matched to an existing Customer by email (case-insensitive); unmatched rows are still stored with customerId=null so a future re-resolve can backfill the link. Idempotent on sourceId. Capped at 500 touches per request.