fix(profile): persist user profile updates to log file

feat(error-handling): add specific error message for quota exhaustion

feat(gemini): implement dynamic model selection in chat interface

fix(gemini): upgrade model to gemini-2.5-flash and remove debug route

feat(debug): add /debug/models route to list available Gemini models

fix(logging): improve error logging with traceback and logger

fix: update gemini model version and add sys import

fix(home): implement correct user profile creation workflow

refactor(chat): use error_redirect template for history errors

Add .env to .gitignore and update genai_service to load API key from environment

refactor: reorganized project by separating routes and services