feat(metaserver): define directory v1 contract

[zoeyrose]

Advances #12.

Summary

• define the bounded Game Protocol 1 static-directory model, canonical JSON schema, freshness/generation/ETag rules, and semantic HTML/XML projections
• generate Go and Rust types and add independent transactional validators with strict DNS-only optional endpoints and certificate identity binding
• add shared positive, negative, maximum-bound, XML, and projection fixtures plus Go fuzz and Rust mutation/truncation coverage
• include the contract and fixtures in release packaging

This deliberately does not close #12 yet: the linked Worker, Go server, and Rust client implementations still need to consume the frozen fixtures and complete rollout.

Validation

• tools/validate.sh
• git diff --check

The ignored deep-review report records three adversarial review passes and the remediations applied. No live deployment changes are included.

[github-actions]

🎉 This PR is included in version 1.2.0 🎉

The release is available on:

• v1.2.0
• GitHub release

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