fix: add missing dependencies itsdangerous and starlette for session middleware

fix: database connection string normalization and improved error logging for cloud deployment

Fix: Add missing ENVIRONMENT and DEBUG settings to prevent AttributeError on 500 errors

Fix: Add SessionMiddleware for Google OAuth and ensure routing synchronization

fix: correct router imports and update docker-compose for decoupled frontend

feat: integrate Google OAuth, ArXiv discovery and project-based analysis

Handle missing OpenAI key for embeddings

Initial clean backend deployment