Fix: Matplotlib permission error

dockerfile

@@ -18,7 +18,7 @@ COPY requirements.txt .
 RUN --mount=type=cache,target=/root/.cache/pip \
     pip install --no-cache-dir -r requirements.txt
 
-# Final stage - using slim instead of alpine
+# Final stage - using slim
 FROM python:3.11-slim
 
 # Install minimal runtime dependencies
@@ -45,6 +45,11 @@ RUN mkdir -p logs embed && \
     chown -R bot:bot /app logs embed && \
     chmod -R 777 /app logs embed
 
+# Create and set permissions for matplotlib config directory
+RUN mkdir -p /tmp/matplotlib && \
+    chown -R bot:bot /tmp/matplotlib && \
+    chmod -R 777 /tmp/matplotlib
+
 # Switch to non root user
 USER bot
 
@@ -53,6 +58,8 @@ ENV PYTHONUNBUFFERED=1
 ENV CONFIG_PATH=/app/config.ini
 ENV PYTHONDONTWRITEBYTECODE=1
 ENV PYTHONPYCACHEPREFIX=/tmp
+ENV MPLCONFIGDIR=/tmp/matplotlib
+ENV MPLBACKEND=Agg
 
 # Run the bot using tini and entrypoint script
 ENTRYPOINT ["tini", "--", "/bin/sh", "entrypoint.sh"]