feat(dns): expose normalized query names

[ryanfowler]

Summary

• render absolute DNS query names when IDNA or single-label qualification changes the inspected name
• preserve service labels and validate normalized names against DNS wire limits
• document direct-DNS query-name behavior

Validation

• go test -v -parallel 8 ./...
• go build .
• staticcheck ./...
• go vet ./internal/dnsinspect ./internal/resolver