Realtime regression in non-English production voice agents: gpt-realtime-mini vs gpt-realtime-mini-2025-10-06

Same issues for gpt-realtime upgrade: GPT-Realtime 1.5 — Major regression in voice expressiveness and accent quality - #4 by rich.gilmour

For voice agents, the first thing the clients care about is actually the voice! Intelligence only comes second (later in the tests/demos).