Publish ACIR JSON Schema

[coderabbitai]

As discussed in PR #55, we should publish a formal JSON Schema for the ACIR JSON format.

Context:
PR #55 introduces JSON representation for ACIR documents with the AcirJsonDocument and related types. Currently, AcirJsonSchema.cs exists as a placeholder, and we need to define and publish a formal JSON Schema to enable validation and tooling support.

References:

• Pull Request: Add cascode convert for ACIR <-> JSON conversion #55
• Comment: Add cascode convert for ACIR <-> JSON conversion #55 (comment)
• Requested by: @daniellovell