Feat/build signup flow

[AAdewunmi]

Summary

Builds and aligns the StudyBuddy signup flow with the current custom user model and Athenify-inspired UI system.

Changes

• Added the active signup workflow through UserSignUpForm.
• Updated signup view handling to create and authenticate new users.
• Refactored templates/users/signup.html to match the current design system.
• Added shared form error styling.
• Updated auth view tests for signup, login, duplicate email handling, and profile access.

Behavior

• Visitors can create a StudyBuddy account from the signup page.
• Signup creates a valid custom user using email-first authentication.
• Username is optional and is generated from the email when omitted.
• Duplicate emails are rejected.
• Successful signup logs the user in and redirects to the dashboard.

Why

Signup is the first real user entry point, so it needs to be consistent with the custom user model, authentication flow, and current product UI.

Validation

• docker compose exec -T web python manage.py makemigrations --merge
• docker compose exec -T web python manage.py migrate --noinput
• docker compose exec -T web python -m black . --check
• docker compose exec -T web python -m ruff check .
• docker compose exec -T web pytest -q

Result

All checks pass. Test suite result: 32 passed.

Notes

The Docker image was rebuilt because this Compose setup copies source into the image rather than mounting the local workspace live.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!