Refactor/issue 29 add pydantic validations

[AmanDeol7]

This pull request refactors data validation in all user-related DTO (Data Transfer Object) classes by replacing custom Pydantic validators with built-in Pydantic Field constraints and Annotated types. The changes ensure that string fields are non-empty and whitespace-trimmed, and numeric fields are within valid ranges, using declarative schema definitions instead of imperative validation methods. This approach improves code readability, maintainability, and leverages Pydantic's built-in validation mechanisms.

Key changes by theme:

Validation Refactoring:

• Replaced all custom @field_validator and @validator methods with Pydantic Field constraints (such as min_length=1, strip_whitespace=True, and numeric bounds like ge=0, ge=1, le=12) and used Annotated types for clarity in all DTO classes (user_entity.py, education_entity.py, certification_entity.py, projects_entity.py, links_entity.py, location_entity.py, publication_entity.py, profile_entity.py). [1] [2] [3] [4] [5] [6] [7] [8]

Schema Improvements:

• Ensured all required string fields (such as names, usernames, IDs) are validated for non-empty values and whitespace is automatically stripped, both in creation and update DTOs. [1] [2] [3] [4] [5] [6] [7]
• Added numeric bounds to relevant integer fields (e.g., months, GitHub stats, total lines contributed) to prevent invalid data entry. [1] [2]

Codebase Simplification:

• Removed all custom validation methods, resulting in cleaner and more maintainable DTO classes. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11]

Consistency and Best Practices:

• Applied a consistent validation approach across all user-related entities, ensuring uniformity and reducing the risk of validation errors. (All references above)

These changes modernize the DTO validation approach, making the codebase more robust and easier to extend.

[JRS296]

@AmanDeol7 Moving to the new validation frame work is fine, but make sure there are not other breaking changes. From my knoweldge I approached it this way to have some synergy with the global test handlers. Kindly make sure everything works as expected

[happydracula]

@AmanDeol7 Moving to the new validation frame work is fine, but make sure there are not other breaking changes. From my knoweldge I approached it this way to have some synergy with the global test handlers. Kindly make sure everything works as expected

Hey @AmanDeol7 if its possible can you share a few screenshots of maybe a couple APIs to show that everything is working fine? We can merge post that changes look good to me