Fix Dockerfile ENV syntax and ensure gdown in requirements

Dockerfile

@@ -1,42 +1,23 @@
-# Start from a Python base image
 FROM python:3.9-slim
 
-# Set environment variables
 ENV PYTHONUNBUFFERED=1 \
-    # Ensures that Python output is sent straight to terminal without being first buffered
-    # and that can be helpful for logging.
     PIP_NO_CACHE_DIR=off \
-    # Disables pip caching, which can reduce image size.
     PIP_DISABLE_PIP_VERSION_CHECK=on \
-    # Disables the check for a new version of pip, speeding up builds.
     PIP_DEFAULT_TIMEOUT=100 \
-    # Increases the default timeout for pip.
     HF_HUB_DISABLE_SYMLINKS_WARNING=1
-    # To suppress the symlink warning from huggingface_hub
 
-# Create a non-root user and switch to it
 RUN useradd -m -u 1000 user
 USER user
-ENV PATH="/home/user/.local/bin:$PATH" # Add user's local bin to PATH
+ENV PATH="/home/user/.local/bin:$PATH"
 
-# Set the working directory in the container
 WORKDIR /app
 
-# Copy requirements.txt first to leverage Docker cache
 COPY --chown=user ./requirements.txt requirements.txt
 
-# Install Python dependencies (including gdown)
 RUN pip install --no-cache-dir --upgrade -r requirements.txt
 
-# Copy the rest of the application code into the container
-# This will include app.py, static/, templates/, LICENSE, README.md
-# AND model_files/tokenizers/ (but NOT model_files/best_model.pth)
 COPY --chown=user . .
 
-# Expose the port the app will run on. HF Spaces expects 7860 for Docker.
 EXPOSE 7860
 
-# Command to run the application using Gunicorn
-# It will listen on all interfaces (0.0.0.0) on port 7860.
-# app:app means "in the file app.py, use the Flask instance named app".
 CMD ["gunicorn", "--bind", "0.0.0.0:7860", "--workers", "1", "--threads", "2", "--timeout", "0", "app:app"]