Fix activity delivery during rolling deployments with multiple worker builds.
Versioned workers can poll unpinned activity tasks as well as tasks pinned to
their own build. Namespace, queue, connection, activity type, readiness and
availability filters remain enforced, and existing claim authority is unchanged.
The complete bridge suite passes on SQLite, PostgreSQL 17.11 and MySQL 8.0.46
(68 tests / 412 assertions on each). Test-first regressions reproduce the old
null/empty-pin exclusion. See #908 and #909.
This is a compatible patch with no schema or worker protocol changes. Pinned
Server images need a separate package update and qualified rebuild; this
library release does not update an already published Server image.