Keep references intact when canonicalizing Draft 3 schemas

[Vansh-kap-98]

Problem

Two rules dropped a $ref while rewriting a schema, changing what it accepts. Neither needs an id.

type_union_distribute_keywords copies a keyword into every type union branch it applies to. When the value holds a reference, or a reference points into it, the copy duplicates it. The canonicaliser repairs references after a transform, but only the origin it recorded beforehand, so the second copy is left pointing at a path that no longer exists and ends up as {}:

{
  "$schema": "http://json-schema.org/draft-03/schema#",
  "type": [
    { "type": "object", "patternProperties": { "^a": {} } },
    { "type": "object", "patternProperties": { "^b": {} } }
  ],
  "properties": {
    "foo": { "type": "integer" },
    "bar": { "$ref": "#/properties/foo" }
  }
}

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[cubic-dev-ai]

No issues found across 3 files

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[augmentcode]

🤖 Augment PR Summary

Summary: This PR preserves local references while canonicalizing Draft 3 schemas.

Changes:

• Tracks schema-valued dependencies as they move into Draft 3 implication wrappers.
• Accounts for pre-existing extends branches when recording each new destination.
• Rewrites references targeting a moved dependency to its new wrapper location.
• Detects type-union keywords whose values contain references or are reference targets.
• Wraps such unions in extends rather than duplicating those keyword values.
• Adds a frame-based helper that identifies affected top-level keywords.
• Retains the existing identifier/anchor duplication safeguard.
• Adds a regression test for a reference inside distributed properties.
• Adds a regression test for a reference into a dependency schema.
• Asserts the resulting reference paths in canonical Draft 3 output.
• Continues validating the expected output against the canonical Draft 3 metaschema.

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