Add @probo/skills multi-agent compliance package

Ship compliance skills and agent plugin wiring for Claude Code,
Codex, OpenCode, and Cursor via Probo MCP (OAuth 2.0). Includes
access-review and missing-signatures workflows, repo-root Git
marketplaces, validation, and npm release CI.

Signed-off-by: Cursor Agent <cursoragent@cursor.com>

Co-authored-by: Bryan FRIMIN <bryan@frimin.fr>

AGENTS.md

@@ -41,3 +41,4 @@ Detailed guides for specific subsystems live in `contrib/claude/`:
 - [`contrib/claude/release/README.md`](contrib/claude/release/README.md) — Release process (per-track version bump, changelog, tag, push)
 - [`contrib/claude/sandbox.md`](contrib/claude/sandbox.md) — Lima sandbox environments (create, manage, access services)
 - [`contrib/claude/n8n.md`](contrib/claude/n8n.md) — n8n community node (resources, operations, GraphQL helpers)
+- [`contrib/claude/skills.md`](contrib/claude/skills.md) — Agent skills package (`@probo/skills`, compliance workflows, Probo MCP)