Remove retired runtime regression guards

[chubes4]

Summary

Remove retired runtime regression guards

What changed

• Applies the verified agent-task candidate.

How to test

1. Run php tests/validate-docs-agent-packages.php; expect passes.

Compatibility

No compatibility impact was recorded by the cook workflow.

Evidence

• CI expected: Homeboy CI after push
• Durable run execution: Succeeded
• Reviewer-resolvable source evidence: Remove retired runtime negative regression guards #144
• gate-1: Passed

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode executor orchestrated by OpenAI gpt-5.6-sol
• Model: openai/gpt-5.6-terra
• Used for: Removed migration-era negative assertions while preserving positive native and security contracts; Chris reviews and owns the change.