Create `AssociatePortModal` component with port/fixed IP selection and integrate `floatingIp.update` mutation for port association

[vlad-schur-external-sap]

Description

Create AssociatePortModal component with port/fixed IP selection and integrate floatingIp.update mutation for port association. This modal enables associating unassociated floating IPs with available ports via PUT /v2.0/floatingips/{id} from list page actions and details page, with port dropdown populated by listAvailablePorts and fixed IP validation.

Acceptance Criteria

• Modal displays floating IP details, port selection dropdown (populated by listAvailablePorts), optional fixed IP field with CIDR validation.
• Handles Success/Error Codes (200 OK success, 400 Bad Request: invalid port/IP, 404 Not Found: port/IP not found, 409 Conflict: port already associated).
• Form validation for required port selection, fixed IP format/range, prevents self-association.
• Loading state during mutation, success closes modal and refreshes list via cache invalidation.
• Error states show field-specific validation errors and modal-level API errors without crashing parent page.

Issues

• Issue 554: Implement update procedure in floatingIpRouter.ts with support for association/disassociation #554
• Issue 575: Implement listAvailablePorts procedure for form options #575