fix(shared): protect against infinite recursion if a pattern references a JSON schema

[markscott-ms]

Description

@ConfuddledPenguin reported an issue during their Advent of CALM, where Copilot generated incorrect schema in a pattern, causing calm validate to fail after many seconds with an out of memory exception.

Here is a minimal pattern that would fail:

{
    "$schema": "https://json-schema.org/draft/2019-09/schema"
}

calm validate -p <filename>.

I traced this to an infinite loop in schema resolution by AJV. If the CALM schema, or JSON Schema Draft 2020-12 is referenced, all is well, but any other JSON Schema Draft leads to an infinite loop.

This PR causes validation to fail quickly and with a meaningful error if AJV seeks to load a JSON Schema:

error [json-schema-validator]:    Error fetching schema from schema directory: Error: Attempted to load standard JSON Schema with ID https://json-schema.org/draft-06/schema. This is not supported.
info [calm-validate]:     Formatting output as json
{
    "jsonSchemaValidationOutputs": [
        {
            "code": "json-schema",
            "severity": "error",
            "message": "Cannot read properties of undefined (reading '$schema')",
            "path": "/",
            "source": "pattern"
        }
    ],
    "spectralSchemaValidationOutputs": [],
    "hasErrors": true,
    "hasWarnings": false
}

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📚 Documentation update
• 🎨 Code style/formatting changes
• ♻️ Refactoring (no functional changes)
• ⚡ Performance improvements
• ✅ Test additions or updates
• 🔧 Chore (maintenance, dependencies, CI, etc.)

Affected Components

• CLI (cli/)
• Shared (shared/)
• CALM Widgets (calm-widgets/)
• CALM Hub (calm-hub/)
• CALM Hub UI (calm-hub-ui/)
• Documentation (docs/)
• VS Code Extension (calm-plugins/vscode/)
• Dependencies
• CI/CD

Commit Message Format ✅

Testing

• I have tested my changes locally
• I have added/updated unit tests
• All existing tests pass

Checklist

• My commits follow the conventional commit format
• I have updated documentation if necessary
• I have added tests for my changes (if applicable)
• My changes follow the project's coding standards

[Copilot]

Pull request overview

This PR fixes an infinite recursion issue in schema validation that occurs when patterns reference JSON Schema drafts other than CALM schema or JSON Schema Draft 2020-12. The fix adds an early validation check to reject attempts to load standard JSON Schemas, preventing AJV from entering an infinite loop.

Key changes:

• Added protection against loading standard JSON Schemas by checking for json-schema.org URLs
• Added unit and E2E tests to verify the fix works correctly
• Code formatting improvements in test files (whitespace cleanup)

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
shared/src/schema-directory.ts	Added check to reject json-schema.org URL references before attempting to load them
shared/src/schema-directory.spec.ts	Added unit test for JSON Schema rejection and cleaned up whitespace formatting
shared/src/commands/validate/validate.e2e.spec.ts	Added E2E tests for both invalid and valid JSON Schema references

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[aamanrebello]

Could use regex matching here, something like http(s?)://..., but this is not a big deal.