Add documentation consistency tests

[Areen-09]

Description

This PR adds automated documentation drift guard tests to ensure repository documentation stays synchronized with the registered skills.

Changes

• Added tests/test_registry_docs.py with checks for:
  • Documentation page exists for every registered skill.
  • Skills index stays in sync with the registry.
  • Example script index parity.
  • Agent loops documentation coverage.
• Updated docs/TESTING.md to include tests/test_registry_docs.py in framework tests.

Type of Change (Matches Issue Templates)

• Skill Proposal: New Skill (Contains manifest.yaml, skill.py, and instructions.md)
• Bug Report Fix: Non-breaking change which fixes an execution error or framework bug
• Doc Fix: Documentation Update
• Framework Feature / RFC Updates: Core Framework Update (Changes to base_skill.py, loader.py, etc.)

Checklist (all PRs)

• My code follows the Agent Code of Conduct.
• I have run python -m flake8 ., pytest skills/ (or skillware test), and pytest tests/ locally (or the subset relevant to this change).
• CHANGELOG.md updated under [Unreleased] if this PR changes user-visible behavior.
• examples/README.md is updated if this PR adds, renames, or removes a runnable script under examples/.

New or updated skill (complete only if this PR adds or changes a skill under skills/)

Not applicable. This PR does not add or modify any skills.

Constitution & Safety (if adding or modifying a skill)

Not applicable. This PR does not add or modify any skills.

Related Issues

Closes #183