[SDK][Feature] Prototype sandbox config floors

[ChazGo]

📖 Description

Why is this change being made?

We need a reviewable proof of concept for an MXC-owned, repository-reviewed catalog of minimum tool requirements, based on the design proposed in microsoft#779. Config floors are compatibility input rather than authorization, so the resolver must return requirements without modifying or overriding the host-authored policy.

This PR intentionally implements the smallest TypeScript SDK seam. Rust and C# parity, stronger tool identity, signed distribution, catalog overlays, rollback, governance, broad cross-platform authoring, and any certification process remain deferred production work.

What changed?

• Added a versioned config-floor catalog and schema with representative git, node, and npm entries
• Added npm-to-node dependency closure, cycle-safe resolution, deterministic union, and explicit undefined results when all requested tools are unknown
• Added project, executable-prefix, npm cache, and npm registry symbol resolution so returned values are literal SandboxPolicy objects
• Added strict catalog validation for malformed data, unsupported fields, missing dependencies, unsafe user-specific paths, wildcards, unknown symbols, and unregistered policy versions
• Added package-copy wiring and a CI validation gate for the catalog artifacts
• Added focused unit coverage and documented the ownership and security boundary

How was the change tested?

• Ran npm run clean, npm run build, and the complete Node SDK unit suite: 417 tests, 398 passed, 19 skipped, 0 failed
• Ran the repository versioning suite: 67 passed, 0 failed
• Ran npm run validate-config-floors
• Ran npm pack --dry-run --json and confirmed the catalog and schema are included in the package
• Ran git diff --check

🔗 References

• docs: add sandbox config floors feature spec microsoft/mxc#779

🔍 Validation

Covered above under How was the change tested?

✅ Checklist

• Signed the Contributor License Agreement
• Linked to an issue
• Updated documentation (if applicable)
• Updated Copilot instructions (if build, architecture, or conventions changed)
• If this PR changes Cargo.lock, the dependency-feed-check check passes (see docs/pull-requests.md)

📋 Issue Type

• Bug fix
• Feature
• Task

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