As a user, I want to pass custom Pydantic schema to the pipeline

## Description

**Context**
Currently, the Pydantic model schema used in the pipeline is statically defined in the repo. This limits flexibility for users who may need to customize the schema without modifying the repository.

**Problem Statement**
The current implementation requires the pipeline to use predefined Pydantic schemas embedded in the code. This restricts external customization and adaptability. Users should be able to pass their own Pydantic schemas at runtime, allowing for more flexible integration and the ability to work with different data models.

## Acceptance Criteria

- Refactor the pipeline to accept a user-defined Pydantic schema at runtime.
- Provide fallback behavior to use the current static schema if no custom schema is passed, maintaining backward compatibility.