Add Pydantic Schemas for OTP Endpoints and Centralized BaseSettings Configuration

[kowshikdontu]

Hi  @Harish-2003 ,

Adding Pydantic schemas under app/schemas/ for all /otp/send-otp and /otp/verify-otp inputs and outputs this will enforce type validation, clean up our endpoint signatures, and generate richer OpenAPI docs.

even after adding the database we need schemas separately to those routes too, for better and clean validations and also,

Centralizing configuration in app/config.py using a Pydantic BaseSettings class so that all Twilio credentials, JWT secrets, and expiration settings are strongly typed, documented, and loaded from a single .env file.

if you are ok, i will add status_code and response_model to routes too.

Could you please assign this to me? I’ll follow the existing code style, include examples in the Pydantic schemas, and Pydantic BaseSettings.

Thanking you!
—  Dontu Kowshik | Contributor ( GSSoc'25 )

[kowshikdontu]

@Harish-2003 After this is merged, please assign the database-related schema validations also.
I’ll also write the corresponding Pydantic schemas with orm_mode = True for methods like get_user_by_phone and create_user to ensure clean validation and response handling that are going to be merged in #14

[kowshikdontu]

@Harish-2003 , look into this when you are free sir #20 (comment)