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>

packages/skills/commands/access-review.md

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+---
+description: Run a semi-automated access review on a Probo campaign (Claude Code slash command).
+argument-hint: [campaign name or id]
+disable-model-invocation: true
+---
+
+# Access review command
+
+Execute the `access-review` skill for campaign `$ARGUMENTS`.
+
+1. Load `skills/access-review/SKILL.md` from the plugin package root.
+2. Load reference docs from `skills/access-review/references/` as directed by
+   the skill.
+3. Follow the skill workflow exactly.
+
+Do not duplicate skill logic here — the skill is the canonical workflow shared
+with Codex and OpenCode.

packages/skills/commands/missing-signatures.md

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+---
+description: Report missing document signatures and pending quorum approvals per person (Claude Code slash command).
+argument-hint: [organization name or id]
+disable-model-invocation: true
+---
+
+# Missing signatures command
+
+Execute the `missing-signatures` skill for organization `$ARGUMENTS`.
+
+1. Load `skills/missing-signatures/SKILL.md` from the plugin package root.
+2. Load reference docs from `skills/missing-signatures/references/` as directed
+   by the skill.
+3. Follow the skill workflow exactly.
+
+Do not duplicate skill logic here — the skill is the canonical workflow shared
+with Codex and OpenCode.