Fix demo data population script authentication issues

[jardahrazdera]

Fix demo data population script authentication issues

What was broken

The demo data script (demo_data.py) couldn't create habits after login - kept getting 401 Unauthorized errors even though the user was successfully logged in.

What I did

• Created a new working script populate_demo.py that properly handles Flask session authentication
• Fixed cookie security settings in app.py (disabled HTTPS-only cookies for local development)
• Added proper weekday fields for weekly habits
• Made the script handle existing users gracefully

Key changes

1. app.py: Changed SESSION_COOKIE_SECURE from True to False for localhost development
2. populate_demo.py: New script using requests.Session() to maintain login state (like a browser would)
3. Added documentation explaining the fix for educational purposes

How to test

cd backend
python populate_demo.py

Then login to the app with demo_user / demo123 and you'll see sample habits with 30 days of tracking data.

Note

I kept the original broken script as demo_data.py for comparison - it's a good example of a common authentication mistake. The working version is populate_demo.py.