feat: email notification for all login attempts (success, denied, error)

feat: add login access log to Google Drive (access_logs/access_log.csv)

Re-add session persistence with secure random tokens

Fix critical session leak: remove shared /tmp session file

Performance optimizations + PPTX presentation generator

Quick wins: cache CSS, fix O(n²) streaming, logging, timeouts, tab safety

Fix auto-login: use prompt=consent to always get refresh_token

Replace localStorage with server-side session file for cross-tab login

Fix localStorage: use window.parent to escape iframe context

Persist checkpoint to disk + cross-tab login via localStorage

Add Hugging Face Spaces deployment support (16GB RAM vs Render 512MB)

Modularize app.py: extract 2700+ lines into 15 focused modules