feat(cloud): skill management + host-scoped sync REST endpoints

Adds the skills:admin router (cloud/sdk/skill_api.py) for cloud-skill CRUD
and per-host entitlement grant/revoke with CSRF/scope/audit, and a
host-scoped router serving incremental per-host sync deltas plus the
agent local-skill inventory report/readback. Both composed into the
Cloud API app. cloud-api suite green (46 passed).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/cloud-platform/cloud/auth.py

@@ -19,6 +19,7 @@ USERS_ADMIN_SCOPE = "users:admin"
 GOVERNANCE_READ_SCOPE = "governance:read"
 GOVERNANCE_ADMIN_SCOPE = "governance:admin"
 LLM_PROVIDERS_ADMIN_SCOPE = "llm-providers:admin"
+SKILLS_ADMIN_SCOPE = "skills:admin"
 
 
 @dataclass(frozen=True)