fix(#52,#54): Fix attribute synchronization for registered store attributes

[mdayaram]

Previously, registered store attributes could show inconsistent values between the store and Rails' attribute system, causing validation failures and incorrect behavior with methods like attributes, *_before_type_cast, and dirty tracking. This fix ensures proper synchronization between both systems.

This PR introduces an AttributesSync module that maintains proper synchronization between store values and registered attributes by:

• Overriding attribute accessors to ensure both systems stay in sync
• Adding lifecycle callbacks to sync values after initialization and database loads
• Fixing the attributes method to return actual store values instead of defaults
• Ensuring proper type casting in both the store and attribute systems

Fixes #52 Fixes #54

Checklist

• [x] I've added tests for this change
• [x] I've added a Changelog entry
• [x] I've updated a documentation (Readme)