Replace json.schemastore.org with www.schemastore.org

[Copilot]

Migrates references from json.schemastore.org to www.schemastore.org subdomain. Schema $id attributes remain unchanged as json.schemastore.org per requirement.

Changes

• Documentation: Updated catalog URL examples, $ref references, and tool integration examples in CONTRIBUTING.md (10 occurrences)
• Build scripts: Extended build-xregistry.js to map both www.schemastore.org and json.schemastore.org domains
• Catalog: Updated $schema reference in src/api/json/catalog.json
• Test files: Migrated $schema references in 38 test files across src/test and src/negative_test
• Schema constraints: Updated $schema enum validators in 6 schemas to accept both old and new URLs for backward compatibility

Preserved

Schema $id attributes retain json.schemastore.org as specified (475+ schemas). Documentation examples demonstrating proper $id usage also preserved.

// Schema files unchanged
{
  "$id": "https://json.schemastore.org/schema.json",  // ✓ Preserved
  
  // But enum constraints now accept both
  "$schema": {
    "enum": [
      "https://json.schemastore.org/schema.json",
      "https://www.schemastore.org/schema.json"       // ✓ Added
    ]
  }
}

Original prompt

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This section details on the original issue you should resolve

<issue_title>Replace all references to json.schemastore.org with www.schemastore.org</issue_title>
<issue_description>### Area with issue?

Web server

✔️ Expected Behavior

Today, there are several places in the code that references json.schemastore.org URLs. They should all be replaced with www.schemastore.org to finalize the move away from the json sub doamin. The $id attributes in the individual schema files, however, should not be updated

❌ Actual Behavior

Today, there are several places in the code that references json.schemastore.org URLs.

JSON, YAML, or TOML file that does not work.

No response

IDE or code editor.

None

Are you making a PR for this?

No, someone else must create the PR.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Replace all references to json.schemastore.org with www.schemastore.org #5114

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[madskristensen]

@hyperupcall I did a fresh PR on removing the last links to json.schemastore.org without touching the $id attributes. Does it look good to you?