Acknowledge workflow retries in Jira

[eshulman2]

Summary

• post a Jira acknowledgement whenever Forge accepts a non-terminal forge:retry signal
• include the workflow node being resumed so users can see what is happening
• keep acknowledgement failures isolated from workflow resumption

Example comment:

Forge accepted the forge:retry request and is resuming the workflow from execute_task_changes.

Validation

• 20 retry-focused worker tests passed
• 34 contract tests passed
• 232 flow tests passed
• Ruff lint and formatting checks passed
• git diff check passed