Add multi-user speaker profiles, collective voice, and mode toggle

Add confidence loop, curiosity engine, and lightweight TTS

Fix Bambara TTS red state + surface detailed errors in UI

Phase 2: Waxal TTS — Bambara voice output + Fula training notebook

Fix: switch LLM to Qwen2.5-72B-Instruct (Gemma not on HF free tier)

Phase 1: Sahel-Voice-Lab — The Memory Loop