Update the emergency address and billing details, verifying a foreign VAT number against VIES

Saves the emergency address and billing details. address, when present, carries street, city and zip all at once - none can be sent alone. company, ico and dic are MERGED with what is already saved: a missing field is left UNCHANGED, only an explicit empty string ("") clears it (for dic, clearing also drops its VIES verification). A foreign EU VAT number is verified against the VIES registry; vies in the response is only filled in when the result carries a verified VAT number (freshly, or from a retained earlier verification). A domestic VAT number (CZ...) is not verified - it does not affect the rate.