MORPH-15040: API docs for cluster UUID support

[sax6575]

• Get All Clusters (GET /api/clusters): adds a repeatable uuid query param that filters the list (?uuid=A&uuid=B); non-matching UUIDs are ignored.
• Get Cluster by ID (GET /api/clusters/{clusterId}): the path segment now accepts either the numeric cluster ID or the cluster UUID string.
• Adds the uuid field to the clusters list-item response schema for parity with the single-cluster schema.

Changes

• components/parameters/clustersUuid.yaml — new cluster-specific uuid query filter param
• components/parameters/clusterIdOrUuid-path.yaml — new id-or-uuid path param (scoped to the get-by-id GET only)
• paths/api@clusters.yaml — wire up the uuid filter on listClusters
• paths/api@clusters@id.yaml — use id-or-uuid param on getCluster; PUT/DELETE unchanged (still numeric ID)
• components/schemas/clusters.yaml — add uuid to list items