feat: add code safety extension

[aymanyaq]

Summary

Added new optional extension to the AI-DLC rules to add enhanced code generation guards for both greenfield and brownfield applications.

For full context and discussion, please see the RFC: #218

Changes

• Code Safety: Adds enhanced code generation guards for common silent failure classes (e.g., middleware context safety, test mock lifecycle pollution, pagination loops, error serialization).

User experience

This extension is opt-in. When a user is in the Requirements Analysis phase, they will be prompted with an opt-in question to enable code safety guards during the Code Generation phase.

Checklist

• I have reviewed the contributing guidelines
• I have performed a self-review of this change
• Changes have been tested
• Changes are documented

Test Plan

• Load the extension during the Requirements Analysis phase and verify the opt-in prompt appears.
• All markdown files have passed markdownlint-cli2.

Acknowledgment

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of the project license.