Create multiple services in a single request.

• Skips services whose legacyId already exists.
• Returns a summary of created, skipped, and error counts.
• Location and resource links come from the request query and follow the same rules as POST /v3/service.
• An omitted locations query on a COMPANY-scoped service links every company location. An empty or blank locations value links none.
• An omitted, empty, or blank resources value links none unless linkAllResources=true.
• linkAllResources=true on a COMPANY-scoped service, with no resource ids, links every company resource. This is a behavior change: callers should pass resources explicitly or use the opt-in. Explicit resource ids still win. The flag does nothing for other scopes.