New circuitforge_core.task_bridge module: ExternalTask (frozen dataclass,
schema v1) plus push_tasks() httpx wrapper. Pilot consumer is Kiwi, pushing
pantry expiry alerts into Focus Flow (AGPL-3.0, external project). The
contract lives in cf-core (MIT) so AGPL and BSL code never share a process
or artifact — each product implements its own exporter/receiver.
No transport server, no auth/token generation, no product-specific
behavior — pure data contract + reusable push helper, same spirit as the
existing sync and tasks modules.
Bump to 0.22.0.
Closes: #66
