🎨 Extract Magic Strings and Numbers to Constants

[safayavatsal]

Problem

Magic strings and numbers scattered throughout codebase, making maintenance difficult.

Solution

1. Create constants files:
   • lib/logic/AppConstants.dart - app-wide constants
   • lib/ui/theme/Dimensions.dart - sizing constants
   • lib/logic/ErrorMessages.dart - error message constants
2. Replace all magic strings/numbers with named constants
3. Makes code more maintainable and refactorable

Estimated Effort

2 hours

Priority

Low - Code quality improvement

Labels

priority:low, type:code-quality, effort:low