feat: add build and test execution extension

[aymanyaq]

Summary

Added new optional extension to the AI-DLC rules that upgrades the Build & Test phase from documentation-only to actual test execution with self-healing iteration, for both greenfield and brownfield applications.

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

Changes

• Build & Test Execution (5 rules, BUILD-TEST-EXEC-001 through BUILD-TEST-EXEC-005):

Key Capabilities:

• Environment Validation Pre-flight (001): Validates dependency installation, test runner configuration, zero-warnings policy, setup file execution verification, and environment isolation checks before any tests run
• Contract Verification (002): Static pre-execution validation that test files align with source files — verifies import paths, identifiers, selectors, mock module paths, pagination contracts, error serialization contracts, and mock lifecycle alignment
• Test Execution and Iteration (003): Runs the actual test suite, categorizes failures, fixes code, and iterates until all tests pass or a blocking issue requires user input
• Inline Test Execution During Code Generation (004): Runs tests immediately after each code generation step produces test files — not deferred to the end
• Results Presentation (005): Ensures completion messages reflect actual test runner output (pass/fail counts), not estimates

Core Design Principles:

• Tests must actually pass — not just exist as documentation
• Contract verification catches structural mismatches before execution
• The self-healing loop iterates until green, not just one attempt
• Inline execution during Code Generation catches issues early

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 automated test execution.

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.