feat: support Hover state import

[intel352]

Summary

• implement read-only provider import for Hover infra.dns and infra.dns_delegation resources
• return typed gRPC Import state instead of an empty response
• document wfctl import usage for existing Hover domains

Verification

• GOWORK=off go test ./internal -run TestHoverIaCServer_Import_ReturnsResourceState -count=1
• GOWORK=off go test ./... -race -count=1
• GOWORK=off go build ./...
• git diff --check

Adversarial review

• Checked unsupported resource types, nil driver output, import-before-initialize behavior, CLI docs accuracy, and Hover unofficial API overpromise risk.
• Fixed docs to use current wfctl import flags (--name, optional --id) instead of provider-direct flags.