Update Dockerfile

Dockerfile

@@ -10,6 +10,8 @@ COPY requirements.txt .
 
 RUN pip install --no-cache-dir -r requirements.txt
 
-EXPOSE $PORT
+# EXPOSE port (use a default value if $PORT is not set at build time)
+EXPOSE 7860
 
-CMD ["sh", "-c", "uvicorn app:app --host 0.0.0.0 --port $PORT"]
+# Use shell form to ensure $PORT is substituted at runtime, with a default of 7860
+CMD uvicorn app:app --host 0.0.0.0 --port ${PORT:-7860}