fix: restructure Dockerfile to install packages as root, then switch to user

Dockerfile

@@ -15,18 +15,16 @@ RUN apt-get update && apt-get install -y \
 
 # Create user for Hugging Face Spaces (following HF Spaces best practices)
 RUN useradd -m -u 1000 user
-USER user
-ENV PATH="/home/user/.local/bin:$PATH"
 
 # Set working directory
 WORKDIR /app
 
 # Copy requirements file
-COPY --chown=user ./requirements.txt requirements.txt
+COPY requirements.txt requirements.txt
 
-# Install Python dependencies (excluding Gradio for API-only mode)
-RUN pip install --no-cache-dir --upgrade pip && \
-    pip install --no-cache-dir --user \
+# Install Python dependencies as root first
+RUN pip3 install --no-cache-dir --upgrade pip && \
+    pip3 install --no-cache-dir \
     fastapi>=0.115.2 \
     uvicorn[standard]==0.24.0 \
     python-multipart>=0.0.18 \
@@ -46,11 +44,16 @@ RUN pip install --no-cache-dir --upgrade pip && \
     huggingface_hub>=0.23.0
 
 # Copy application code
-COPY --chown=user . /app
+COPY . /app
 
 # Create upload directories with proper permissions
 RUN mkdir -p uploads/source_images uploads/target_videos uploads/result_videos uploads/output && \
-    chmod -R 755 uploads
+    chmod -R 755 uploads && \
+    chown -R user:user /app
+
+# Switch to user
+USER user
+ENV PATH="/home/user/.local/bin:$PATH"
 
 # Set environment variables
 ENV PYTHONUNBUFFERED=1
@@ -60,4 +63,4 @@ ENV CUDA_VISIBLE_DEVICES=0
 EXPOSE 7860
 
 # Run the API server on port 7860 (HF Spaces requirement)
-CMD ["uvicorn", "api_server:app", "--host", "0.0.0.0", "--port", "7860"]
+CMD ["python3", "-m", "uvicorn", "api_server:app", "--host", "0.0.0.0", "--port", "7860"]