Feature: Parallel Action Execution

[benrowe]

Description

Support concurrent execution of independent actions to improve workflow performance.

Acceptance Criteria

Given multiple independent actions
When they are marked as parallelizable
Then they should execute concurrently
And the workflow should wait for all to complete

Technical Notes

• Actions would need a way to declare they are parallelizable (e.g., Parallelizable interface or metadata)
• StateWorker would need to detect parallelizable actions and use async execution
• This may require PHP 8.1+ Fibers or a separate async execution library
• Error handling becomes more complex with concurrent execution

Related

• Original scenario: 13.5 from acceptance-tests.md
• Priority: Low (future enhancement)
• Complexity: High