fix(McpClientTool): Dereference input schema before converting to Zod

[shaharluftig-exp]

Summary

This PR fixes an issue where JSON schemas containing $ref references were not properly resolved before being converted to Zod schemas in the McpClientTool. This was causing validation errors when using schemas with $ref definitions.

Changes made:

• Added schema dereferencing step in McpClientTool before Zod conversion
• Ensures all $ref references are properly resolved to their actual schema definitions
• Handles both internal references (#/definitions/...) and nested $ref structures
• Prevents validation errors when using complex JSON schemas with references

How to test:

1. Create a workflow with a node that uses JSON schema validation
2. Use a schema with $ref like:

   {
     "$schema": "http://json-schema.org/draft-07/schema#",
     "type": "object",
     "properties": {
       "user": { "$ref": "#/definitions/user" }
     },
     "definitions": {
       "user": {
         "type": "object",
         "properties": {
           "name": { "type": "string" },
           "age": { "type": "number" }
         }
       }
     }
   }

3. Verify that the schema is properly resolved and validation works correctly
4. Test with nested $ref and circular reference cases to ensure proper error handling

Related Linear tickets, Github issues, and Community forum posts

Closes #15603

Review / Merge checklist

• PR title and summary are descriptive. (conventions)
• Docs updated or follow-up ticket created.
• Tests included.
• PR Labeled with release/backport (if the PR is an urgent fix that needs to be backported)

[CLAassistant]

All committers have signed the CLA.

[Joffcom]

Hey @shaharluftig-exp,

Thanks for the PR, We have created "GHC-2196" as the internal reference to get this reviewed.

One of us will be in touch if there are any changes needed, in most cases this is normally within a couple of weeks but it depends on the current workload of the team.

[cubic-dev-ai]

cubic reviewed 3 files and found no issues. Review PR in cubic.dev.

[ShireenMissi]

@cubic-dev-ai please review

[cubic-dev-ai]

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[cubic-dev-ai]

No issues found across 4 files