API key management and billing strategy

[freesoft]

Phase 3: LLM Cost Management

Single Gemini API key shared by all users (web_tutor.py:58-60). Free tier: 15 req/min, 1500 req/day.

Tasks

• Evaluate paid API plans
• Design usage-based billing or subscription model
• Consider per-user API key option

Files

• web_tutor.py, .env