Feature/spectral rule leading capability

[andreyyudin]

Closes #7

Summary

This PR adds a new Spectral rule enforcing that all OpenAPI specifications explicitly declare the leading business capability through the info.x-leading-capability field. This ensures every API is traceable to its primary business capability as defined in LeanIX.

Changes Made

Spectral Rule: info-leading-capability

• Introduced a new rule requiring info.x-leading-capability in all OpenAPI files.

• Validation checks that the value matches one of the approved UKHSA Business Capabilities.

• Custom error message for violations:

  Missing or wrong 'info.x-leading-capability', should be a valid UKHSA Business Capability.

UKHSA Business Capabilities List

• Added a new TS file defining the list of valid business capabilities and a script that generates such files. The input to the script is the XML file that one can export from LeanIX. To export open https://phe.leanix.net/phelive/diagrams/freedraw/191bf94d-4c5e-4547-9f26-d128d802faf4?returnUrl=%2Fdiagrams%2Foverview%2Fall-diagrams, click "⋮" in the top right corner -> Export -> diagrams.net XML file.
• The generator also populates the list of UKHSA Business Capabilities in documentation.

Documentation Updates

• Extended API linting documentation with details of the new rule.
• Included guidance on how to set the correct x-leading-capability value and fix validation errors.

Example Specifications

• Added valid and invalid OpenAPI examples to demonstrate compliance and failure scenarios.

  • Valid example includes a correct info.x-leading-capability value.
  • Invalid examples cover missing or unrecognized capability names.

[github-actions]

Test Results

 1 files  ±0   9 suites  +2   10s ⏱️ ±0s
54 tests +6  54 ✅ +6  0 💤 ±0  0 ❌ ±0 
55 runs  +6  55 ✅ +6  0 💤 ±0  0 ❌ ±0 

Results for commit ca47925. ± Comparison against base commit 262285b.