fix: resolve $ref in OpenAPI 3.1 schema fields

[reuvenharrison]

Summary

• Fix resolveSchemaRef to resolve $ref references inside OpenAPI 3.1 / JSON Schema 2020-12 schema fields

Problem

When loading an OpenAPI 3.1 document that uses $ref inside any of the new JSON Schema 2020-12 fields, the referenced Schema.Value remained nil because resolveSchemaRef only processed pre-3.1 fields (items, properties, additionalProperties, not, allOf, anyOf, oneOf).

Example that failed:

openapi: "3.1.0"
components:
  schemas:
    StringType:
      type: string
    TupleArray:
      type: array
      prefixItems:
        - $ref: "#/components/schemas/StringType"  # This ref was not resolved

The following fields were affected:

• prefixItems — tuple validation schemas
• contains — array containment schema
• patternProperties — pattern-based property schemas
• dependentSchemas — conditional schema dependencies
• propertyNames — property name validation schema
• unevaluatedItems — unevaluated array items schema
• unevaluatedProperties — unevaluated object properties schema

Solution

Add ref resolution for all OpenAPI 3.1 schema fields in resolveSchemaRef, following the same patterns already used for the existing fields.

Related

Follow-up to PR #1114 (OpenAPI 3.1 support).

Test plan

• New test TestResolveSchemaRefsIn31Fields verifies all 7 field types resolve correctly
• All existing tests pass

🤖 Generated with Claude Code

[reuvenharrison]

Superseded by #1125 which consolidates all OpenAPI 3.1 PRs into a single PR.