fix: rewrite composed refs inside extensions

[matoous]

Composed bundles could leave root-level vendor extension $refs pointing at external files even when the referenced component had been composed into the bundle. Such refs made the bundled document not self-contained.

Allow the final composed-ref rewrite pass to also process $ref values under x-* extension fields, and add a regression test.

Spotted on our side once we upgraded to the latest vacuum version. In our case, we use extensions similarly to the included regression tests which stopped being properly composed.

Related: 8585a05

[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 99.76%. Comparing base (d4c45ce) to head (cea59aa).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
bundler/composer_functions.go	75.00%	3 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #602      +/-   ##
==========================================
+ Coverage   99.75%   99.76%   +0.01%     
==========================================
  Files         281      283       +2     
  Lines       34061    34442     +381     
==========================================
+ Hits        33977    34362     +385     
+ Misses         51       49       -2     
+ Partials       33       31       -2     

Flag	Coverage Δ
unittests	99.76% <75.00%> (+0.01%)	⬆️

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[daveshanley]

Thank you for your contribution!

one case that still leaves the composed bundle non-self-contained.

The patch rewrites extension $refs when the complete target exactly matches an entry in processedNodes, but not when the ref points below a composed component. For example:

x-related-field:
  $ref: './models.yaml#/components/schemas/Thing/properties/id'

If Thing is composed elsewhere, the bundle contains #/components/schemas/Thing, but the extension still retains the external ./models.yaml#... reference.

Could resolveRefToComposed find the longest composed ancestor and append the remaining JSON Pointer suffix? A regression test using a nested target such as Thing/properties/id would cover this case.