Outbound WhatsApp template sends now pin the immutable template version used at send time.
- Stores
template_version_idon outbound template messages and campaign recipients. - Propagates the pinned version through outbox payloads for one-off, transactional API, and campaign sends.
- Dispatch prefers the pinned immutable version instead of re-reading mutable current template state.
- Adds DB validation so template version references stay inside the same workspace.