Finalize AI English Tester — Add Listening Module & CEFR Evaluation (TypeScript + Vercel + Gemini AI + Supabase + ElevenLabs) Description: We already have a working MVP built with TypeScript (Next.js), hosted on Vercel, and integrated with Google Gemini AI, Supabase, and ElevenLabs. The product is an AI-based English proficiency tester that conducts online interviews (Speaking, Writing) and evaluates users’ language level according to the CEFR (A1–C2) standard. This is a project improvement task, not a new development from scratch. Tasks: Implement the Listening module (audio playback + questions + evaluation). Build the final CEFR evaluation logic, combining results from all modules. Integrate results into Supabase. Perform stability and validation testing. Deliverables: Functional Listening module. Valid CEFR-based scoring system. Bug-free and stable MVP. Preferred experience: Google Gemini AI / OpenAI API integrations. Supabase, Vercel, ElevenLabs API. Experience with CEFR or AI-based language assessment.