VouchSpec Stage A alpha v0.2.0

Public read-only Stage A alpha: 25 signed exact-version Agent Skill receipts across 12 GitHub repository-owner namespaces (publisher identity and corporate independence unverified), 19 structural passes, six explicit failures, and zero artifact execution. Includes DSSE/Ed25519 verification, root-signed lifecycle state, static TLS/CORS retrieval, and installable stdio MCP. Paid orders, uploads, private artifacts, and Stage B validation are disabled. Full suite: 53 passed, one documented Windows symlink-privilege skip. No open-source license is granted by this release.