Portraits step 2: /portrait engine routing + imagen facade + Settings picker

Settings: recommended quality presets + device readout; persist all choices

Voice: provider-driven per-hero voices; settings is provider-only

Persona: simplify prompt to name/about/quote/voice; editable in Settings

Move Voice settings into the Settings page; add a sidebar ⚙ Settings button

Fix empty-JSON: keep the answer when a model leaves <think> unclosed

Settings: model section to top; default WebLLM + Qwen3 0.6B; copyable debug

Put the model picker in Gradio's OWN settings page (not a custom tab)

Move engine/model settings to a Settings page; share one model across both pages