Associate the floating IP with a target resource

Associates ("Associate" in the floating IP detail page and the list row menu) the selected floating IP with a target resource — a virtual machine port or a load-balancer VIP chosen from the associate dialog. On success the address transitions to status ACTIVE and its fixedIp, instance, port, and router fields are populated from the target; the resulting state is available to subsequent reads. Supply targetFixedIp to pin the association to one NIC of a multi-NIC target; omitted, the first bindable port is used. Validation: floating IP must exist and be visible in the scope → 404 NOT_FOUND; targetId must reference an instance/port reachable in the scope → 404 NOT_FOUND (settled against the provider); current state must permit association (the address must not already be associated) → 409 CONFLICT; caller needs contributor or higher → 403 FORBIDDEN; malformed body → 422 VALIDATION_FAILED. Async & state: Asynchronous: 202 with an Operation. The port binding is performed against the network fabric and the address settles ACTIVE (or the Operation ends FAILED); a resource.updated SSE frame (kind: network.floating_ip, patch: {status, fixedIp, instance, port, router}) is emitted so open list/detail views refresh without polling. Errors: 401 unauthenticated; 403 missing permission; 404 unknown floating IP or target; 409 CONFLICT when already associated or the address state forbids association; 422 invalid body; 429 rate limited; 500 internal failure. Idempotency/Concurrency: Idempotency-Key is optional (recommended); replaying a key returns the original 202 Operation rather than binding twice. This operation does not check If-Match; a sent one is ignored (an address that is already associated is the 409 above).