docs: add workflow_dispatch trigger to CI workflow example

[jeremyeder]

Summary

Adds workflow_dispatch trigger to the CI workflow example in the AQE pattern documentation.

This allows manual re-triggering of workflows, which is useful when:

• CI fails due to transient issues (network, rate limits)
• Branch protection bypass settings need testing
• Debugging workflow behavior

Changes

• Added workflow_dispatch: to the validate.yml example in autonomous-quality-enforcement.md

This aligns with the stale-issues.yml example which already includes workflow_dispatch.