feat: vendor Casper (CSPR.cloud) official skill

[mssteuer]

What this adds

This PR vendors the official Casper skill, published by CSPR.cloud, into the catalog:

• vendored/casper/cspr-cloud/SKILL.md — fetched byte-for-byte from https://cspr.cloud/skill.md
• vendored/casper/cspr-cloud/LICENSE — permission notice, mirroring the existing Privy/Humanode convention
• skills-lock.json — new cspr-cloud entry (owner casper, sourceType: https, fetch: curl), inserted in alphabetical order
• NOTICE.md — credits row in its alphabetical position
• vendored/README.md and README.md — catalog rows, plus Casper added to the Layer 5 (execution) row and the vendored counts refreshed to 91 skills / 33 owners

Official source

The skill is published by CSPR.cloud at the canonical URL https://cspr.cloud/skill.md and documented as the official AI skill at https://docs.cspr.cloud/agentic-tools/ai-skill.md. CSPR.cloud is the Casper Network infrastructure provider (MAKE Software). This is the same official-source pattern already vendored here for Privy, AntSeed, Humanode and Intelligent Oracle — a canonical skill.md served from the vendor's own domain, fetched with curl.

The skill itself covers the CSPR.cloud REST API, the Streaming API, the Casper Node RPC/SSE proxy, indexed Casper chain data, and pagination/filtering/error conventions.

License

Upstream publishes no explicit open-source license, so we use the repository's existing LicenseRef-Permission convention: the copy is redistributed with the owner's explicit permission, the owner's copyright is reserved, and no open-source license is asserted. The LICENSE file wording matches vendored/privy/privy/LICENSE exactly, with the holder and source substituted.

Why Casper belongs in an agent-commerce catalog

Casper runs a live x402 facilitator at https://x402-facilitator.cspr.cloud, documented under https://docs.cspr.cloud/x402-facilitator-api/ (reference, supported, verify, settle), serving CAIP-2 networks casper:casper and casper:casper-test with wCSPR (CEP-18) settlement, plus SDKs at make-software/casper-x402 and @make-software/casper-x402 on npm. The skill vendored here is the CSPR.cloud data/API skill — the Layer 5 execution and chain-data rail behind that facilitator. We deliberately did not add x402 content to the vendored file: the copy is faithful to upstream.

Verification

• sha256sum vendored/casper/cspr-cloud/SKILL.md → e52e2560ad5173352e955d48408ac0810ea9448145236758af3f2d49d824dab8, matching computedHash in the lock file.
• Re-fetching upstream reproduces it exactly: curl -sL https://cspr.cloud/skill.md | sha256sum yields the same digest.
• skills-lock.json parses cleanly, contains 91 skills, and the skills keys remain alphabetically sorted.
• The vendored file has valid YAML front matter with name: cspr-cloud.
• Both markdown links added resolve with HTTP 200.

Scope

Purely additive. No existing skill, lock entry, credit row or catalog row was removed. The only lines touched in pre-existing files are the two README.md lines that had to change for consistency — the vendored counts (90/32 → 91/33) and the Layer 5 list, which now includes casper/.