chore(deps): bump ACP schema to 1.4.0

[OldKrab]

Summary

• Bumps the generated ACP schema dependency from 1.1.0 to 1.4.0 so the Rust SDK exposes the latest unstable elicitation option description field.
• Updates v2 JSON-RPC mappings for the schema 1.4.0 generated names and boxed enum payloads.
• Keeps removed schema feature flags as empty compatibility aliases in the SDK feature surface.
• Removes the obsolete URL-required error fallback from Testy coverage; unsupported URL elicitation is now skipped according to client capabilities.
• Adjusts compatibility tests for schema 1.4.0 initialize metadata requirements and adds coverage that enum options serialize descriptions.

[OldKrab]

@benbrandt Hi, could you take a look when you have time?

[benbrandt]

thanks for taking a look but I think I want to take a different approach with some of these items. Will have it up soon