Parametrize ai_operator_default_config() via AI_OPERATOR_* env vars,
falling back to the existing hardcoded defaults so the other two stacks
(call-center, sales-call-center) that share this code are unaffected.
Set aimaq-only overrides matching the client-provided script (Скрипт
ии-оператора КГА.docx): agent renamed to Жанна, company to Казакгаз
Аймак, the voice greeting now asks the caller whether Russian or
Kazakh is more convenient before anything else, and the base system
prompt instructs the model to commit to whichever language the caller
picks for the rest of the call, ask how to address them, and confirm
there's nothing else before saying goodbye.