chore(server): update Dockerfile to bind to dynamic PORT and adjust CMD for FastAPI application

Dockerfile

@@ -31,5 +31,7 @@ COPY . /app
 RUN useradd -m appuser
 USER appuser
 
-EXPOSE 8000
-CMD ["uvicorn", "app:app", "--host", "0.0.0.0", "--port", "8000"]
+ENV PORT=7860
+EXPOSE 7860
+
+CMD ["sh", "-c", "uvicorn main:app --host 0.0.0.0 --port ${PORT}"]