Refactor database initialization and remove Alembic migrations

- Removed legacy Alembic migration files and consolidated schema management into a new Pydantic-backed initializer (`scripts/init_db.py`).
- Updated `main.py` to ensure the new DB initializer runs on startup, maintaining idempotency.
- Adjusted session management in `config/database.py` to prevent DetachedInstanceError.
- Introduced new enums in `models/enums.py` for better organization and clarity.
- Refactored various models to utilize the new enums, improving code maintainability.
- Enhanced middleware to handle JSON validation more robustly, ensuring non-JSON requests do not trigger JSON errors.
- Added tests for middleware and enums to ensure expected behavior and consistency.
- Updated changelog to reflect significant changes and improvements.

Dockerfile

@@ -102,13 +102,12 @@ RUN pip install --upgrade pip \
 
 COPY . /app
 
-RUN chown -R appuser:app /app \
-    && chmod +x /app/scripts/docker-entrypoint.sh
+RUN chown -R appuser:app /app
 
 USER appuser
 
 EXPOSE 8003
 
-ENTRYPOINT ["/app/scripts/docker-entrypoint.sh"]
+ENTRYPOINT ["uvicorn"]
 
-CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8003", "--workers", "4"]
+CMD ["main:app", "--host", "0.0.0.0", "--port", "8003", "--workers", "4"]