Refactor code structure for improved readability and maintainability

Author: nim444

.docs/endpoints.png

@@ -10,6 +10,8 @@
 
 A robust FastAPI application demonstrating user registration, JWT authentication (including refresh tokens), and a flexible repository pattern supporting SQLite, PostgreSQL, and MongoDB backends.
 
+![Endpoints](.docs/endpoints.png)
+
 ## Purpose
 
 This project serves as a template or starting point for building secure and scalable FastAPI applications with a focus on:
@@ -19,12 +21,6 @@ This project serves as a template or starting point for building secure and scal
 * **Modern Tooling:** Utilizes `uv` for dependency management, `Dynaconf` for configuration, and `ruff` for linting/formatting.
 * **Testability:** Designed with dependency injection and includes a comprehensive test suite using `pytest`.
 
-## User Interface
-
-Below is a preview of the application's interface:
-
-![User Interface](.docs/interface.png)
-
 ## Highlights
 
 * JWT-based authentication (login, refresh tokens).
@@ -82,6 +78,12 @@ Below is an overview of the application's architecture:
 └── uv.lock               # Lock file for dependencies (uv)
 ```
 
+## User Interface
+
+Below is a preview of the application's interface:
+
+![User Interface](.docs/interface.png)
+
 ## Setup and Installation
 
 1. **Clone the repository:**