Workflow 2.7.2

Update request identity and intake refusals

• Keep an update's caller key independent of proxy request-correlation headers.
  Preserve opaque case, long Unicode keys and retained legacy receipts; return
  the earliest receipt if older code admitted duplicates.
• Check pending-update and payload limits before the missing-local-definition
  gate. Retain inspectable rejections with the limit kind, value and configuration.

Upgrade direct database writers together

New update rows use bounded update-v1: tokens in the internal indexed
workflow_commands.request_id column. Read logical keys through
WorkflowCommand::requestId() or command context. Existing rows are preserved.

Drain and upgrade all processes writing directly to the database before
admitting new updates. After the new format is written, an old writer is an
unsafe rollback target. Remote SDK clients keep the same HTTP contract.

Self-hosted Server adoption is a separate coordinated release. This library
tag does not update a pinned Server image; keep its supported package pin.

Related: Server #505,
Server #506,
Core implementation #862.