fix(schema-model): improve logic for resolving circular refs and use when removing readonly fields

[vaibhavrajsingh2001]

Summary

Some specs with circular refs in Schema Objects were failing parsing.
Reason: removeFieldsFromSchemaObject previously relied on JSON.parse(JSON.stringify) cloning, which fails for circular refs.

Changes:

• if stringify fails in removeFieldsFromSchemaObject then resolve circular refs
• implement a DFS stack based approach to resolve circular refs, as the old Set+JSON replacer approach only avoids revisiting repeated refs but still depends on recursive serialization and was causing max call-stack reached errors
  • iteratively traverses the object graph using an explicit DFS stack,
  • tracks seen objects with WeakMap,
  • drops repeated/circular references to produce a safe tree-shaped clone.
• add tests for circular refs in removeFieldsFromSchemaObject

Portal verification PR: https://github.com/kong-konnect/portal/pull/2097

[vaibhavrajsingh2001]

Resolves https://konghq.atlassian.net/browse/TDX-7645

[adamdehaven]

We need to find what's actually throwing the error and properly catch it. It looks like there are still 500 errors during SSR in the portal

[kongponents-bot]

Install the preview package from this PR

@kong/spec-renderer@pr-810