feat(cloud): cloud-managed skill store + per-host entitlement + sync versioning

Adds cloud/skills.py (domain + service), SQLAlchemy models and Alembic
migration 0010_skill_management (cloud_skills, cloud_skill_entitlements,
cloud_skill_sync_state, a per-host changelog, and host_skill_inventory),
and repository methods with a monotonic per-host entitlement_version that
drives correct incremental fetch_host_delta. cloud-api suite green (41
passed); HEAD_REVISION bumped to 0010.

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

packages/cloud-platform/cloud/schema.py

@@ -9,7 +9,7 @@ from alembic.runtime.migration import MigrationContext
 from cloud.database import create_database_engine, normalize_database_url
 
 
-HEAD_REVISION = "0009_planner_decision_log"
+HEAD_REVISION = "0010_skill_management"
 
 
 class SchemaVersionError(RuntimeError):