List IKE (Phase 1) policies in the active scope

Returns the paginated collection of IKE (Phase 1) policies in the active scope. An IKE policy is a FIRST-CLASS, REUSABLE resource that mirrors the neutron-VPNaaS ikepolicies resource one-for-one: one policy may be referenced by many IPsec site connections, and is never cloned per connection. Each row carries the negotiated algorithm set (auth, encryption, PFS group, IKE version, phase-1 negotiation mode), the security-association lifetime as neutron's own units+value pair, this record's provisioning state and usedByCount - how many site connections currently reference it, which is what makes a delete or an update of an in-use policy fail. Validation: scopeId must resolve to an accessible scope (unknown/forbidden scope -> 403 or 404); region, sort, order, page and pageSize must be well-formed (malformed paging -> 422 VALIDATION_FAILED); caller needs at least the reader role on the scope, otherwise 403 FORBIDDEN. Async & state: Synchronous read; no state change. Errors: 401 when unauthenticated; 403 when the caller lacks read permission on the scope; 422 when query parameters fail validation; 500 on backend read failure. Idempotency/Concurrency: Safe, cacheable; no idempotency key required. Soft-deleted policies are excluded (deleted_at IS NULL).