Enhance Dockerfile: add user creation step and improve package installation process

Dockerfile

@@ -1,5 +1,6 @@
 FROM python:3.13.5-slim
 
+RUN useradd -m -u 1000 user
 WORKDIR /app
 
 RUN apt-get update && apt-get install -y \
@@ -8,10 +9,10 @@ RUN apt-get update && apt-get install -y \
     git \
     && rm -rf /var/lib/apt/lists/*
 
-COPY requirements.txt ./
-COPY src/ ./src/
+COPY --chown=user requirements.txt ./
+COPY --chown=user src/ ./src/
 
-RUN pip3 install -r requirements.txt
+RUN pip3 install --no-cache-dir --upgrade -r requirements.txt
 
 EXPOSE 8501