[Conformance] Shared Cross-Language Test Suite Implementation

[tercel]

Problem Description

While conformance/fixtures/ exists with JSON files (e.g., acl_evaluation.json, normalize_id.json), there isn't a standardized, automated runner to verify these across all SDKs (Python, TypeScript, Rust, Go, etc.) to ensure 100% behavioral parity.

Why solve it

Consistency is a core promise of apcore. A module defined in one language must behave identically in another. Manual verification is error-prone as the spec grows.

• Interoperability: Ensuring consistent execution across different platforms.
• Regression Prevention: Catching bugs early when updating SDKs or the core spec.
• Trust: Providing a reliable 'Conformance Suite' for third-party SDK developers.

How to solve it

1. Runner Framework: Create a test runner (likely in Rust or Python) that consumes conformance/fixtures/*.json.
2. Standardized Interface: Define a 'Conformance Driver' (e.g., a simple CLI or JSON-RPC wrapper) for each SDK to implement.
3. Automated CI: Integrate the runner into the CI pipelines of all official SDK repositories.
4. Coverage: Expand the fixtures to cover more complex scenarios like the 11-step execution pipeline, streaming, and error propagation.