Support self-referential structures

[BrodyEller]

Describe the bug
When attempting to generate a jsonschema using a struct that references itself(jsonschema.Schema for example), an error is returned: cycle detected for type jsonschema.Schema. This error is coming from jsonschema/infer.go

To Reproduce
Steps to reproduce the behavior:

1. Generate a jsonschema using jsonschema.Schema or any other struct that references itself.

Expected behavior
Generate a ref instead of erroring

Logs
cycle detected for type jsonschema.Schema

Additional context
For reference, my use case is accepting a json schema as input to an MCP tool.

[RPGillespie6]

This is a pretty annoying limitation since self-referential structures show up all the time in real APIs. For example:

• JIRA issues can be self referential (JIRA issues can reference other JIRA issues)
• A lot of text formatting data structures are self referential. For example BitBucket PR descriptions take a "TextContent" object, which, among other things can have children "TextContent" objects