CON-1534: centralize Vast agent skills

[jjziets]

Summary

• establish vast-ai/skills as the canonical source for the Vast renter, host, and host-support Agent Skills
• add a versioned bundle manifest and a reusable materializer that generates pinned wrapper snapshots
• add cross-platform canonical validation and a reusable workflow that opens wrapper sync PRs
• preserve canonical skill bytes as LF across operating systems so revision hashes are reproducible
• expose a skills-only Claude marketplace bundle
• update host diagnostics for vast-cli PR Add HAM (Hierarchical Agent Memory) skill anthropics/skills#458 TCP/UDP configured-range scanning

Why

The Claude, Codex, and Cursor plugin repositories currently contain nine checked-in skill files but only three unique files. Corresponding files are byte-for-byte identical, so every correction has to be repeated across three repositories.

Harness packages still require local skill paths. This PR makes those local files generated release artifacts rather than independent source:

1. Edit a skill once in vast-ai/skills.
2. Wrapper sync automation copies the complete skill directories.
3. Each wrapper records the canonical Git revision and file hashes in skills.lock.json.
4. Wrapper CI rejects hand-edited snapshot drift.

The harness repositories keep their native manifests, Claude commands, Codex prompts, Cursor rules, installers, and platform-specific tests.

CLI alignment

The host and host-support skills now document the pending vast-cli PR anthropics#458 behavior:

• configured direct-port capacity is range size plus four fixed mappings
• every configured port is mapped and probed over TCP and UDP
• --port-scan-timeout availability must be checked before claiming full-range coverage
• the matching self-test image responder is a paired dependency
• failures preserve structured missing-mapping and per-protocol evidence

The shared guidance is harness-neutral, including private 2FA handling.

Validation

• canonical validator passed
• all three skills passed the standard Agent Skills validator
• sync and check round-trip passed
• generated Codex wrapper passed plugin validation and installer smoke
• workflow YAML parsed successfully
• canonical CI passed on Ubuntu, macOS, and Windows

Rollout

Dependent wrapper PRs pin canonical commit 44ec627a44453e9f4860ed7075123f538d84c6cb:

• vast-ai/vast-claude-plugin#2
• vast-ai/vast-codex-plugin#2
• vast-ai/vast-cursor-plugin#2

Merge this PR first so the pinned revision and reusable sync workflow exist on canonical main.