Evaluate and plan UI beyond Gradio

[brylie]

Gradio works for prototyping but has fundamental accessibility and mobile limitations. The target demographic is likely mobile-first — many recent immigrants do not own laptops. This decision should be time-boxed, not left open-ended.

Checklist:

• Audit current Gradio UI against WCAG 2.1 AA criteria
• Assess mobile usability on representative devices
• Evaluate alternatives (e.g., a lightweight Next.js/React frontend against a FastAPI backend)
• Write recommendation ADR in docs/ within a single sprint — make the call and move on

Note: This is higher priority than it may appear. Delay here blocks meaningful accessibility and UX improvements across the board.