Update Dockerfile

Dockerfile

@@ -25,7 +25,7 @@ COPY requirements.txt .
 RUN pip install --no-cache-dir --upgrade pip && \
     pip install --no-cache-dir -r requirements.txt
 
-# Pre-download models during build (optional, speeds up first request)
+# Pre-download the lightweight model during build (speeds up first request)
 RUN python -c "from rembg import new_session; new_session('u2netp')" || true
 
 # Copy application code