fix: Rewrite nested whole document external refs to components (#1889)

[ewaostrowska]

Pull Request

Description

When an external file referenced by an OAS document contains its own refs that point to other files as whole-document references (no # fragment), the parser resolved the file path but never rewrote the $ref to an internal component form. The resolved output kept raw file paths like ../common/models/Product.yaml instead of #/components/schemas/Product, making the resolved spec unusable for code generators and other consumers.

Before: items.$ref stayed as an absolute file path

items:
  $ref: /abs/path/to/common/models/Product.yaml 

After: items.$ref is rewritten to an internal ref

items:
  $ref: '#/components/schemas/Product'

The same bug affected headers, links, and examples .

Fragment refs (file.yaml#/components/schemas/X) were already handled correctly by the existing code and are not affected by this change.

Fixes: #1889

Type of Change

• 🐛 Bug fix
• ✨ New feature
• ♻️ Refactor (non-breaking change)
• 🧪 Tests
• 📝 Documentation
• 🧹 Chore (build or tooling)

Checklist

• I have added/updated tests as needed
• I have added/updated documentation where applicable
• The PR title is descriptive
• The code builds and passes tests locally
• I have linked related issues (if any)

Screenshots / Additional Context