docs: Add deployed link and API key note to README

Fix: Use prefer-binary flag for pip installation

Fix: Use binary-only installation first, fallback to source if needed

Fix: Add Python version and upgrade pip to avoid Rust compilation issues

Fix: Downgrade pydantic to avoid Rust compilation issues

Fix: Remove uvicorn[standard] to avoid Rust compilation issues on Render

Add API key input in UI, processing time notes, standard resume format, and deployment files

Initial commit: InternHub AI - FastAPI application with Gemini API integration