feat(auth,capstone): validate email on password reset, convert images to webp and add team carousel

- Add email deliverability verification (MEV) to forgot password flow (lookupResetOptions & sendEmailOtp)
- Validate recipient email format and verify deliverability before sending reset password link in user management
- Convert all backdrops, group photos, and solo avatars to WebP format, drastically reducing asset footprint from >60MB to ~4.6MB
- Add auto-advancing slide preview carousel with 2s cooldown, navigation buttons, and wrapping to Capstone Members screen
- Update Capstone member emails and add individual solo avatar photos

frontend/pubspec.yaml

@@ -106,6 +106,8 @@ flutter:
   # To add assets to your application, add an assets section, like this:
   assets:
     - assets/images/
+    - assets/images/group/
+    - assets/images/solo/
     - assets/lottie/
     - assets/sounds/
     - assets/templates/School-Form-10-JHS.xlsx