Refactor code structure for improved readability and maintainability

workers/colorize/Dockerfile

@@ -0,0 +1,24 @@
+FROM nvidia/cuda:12.1.1-cudnn8-runtime-ubuntu22.04
+
+ENV DEBIAN_FRONTEND=noninteractive \
+    PIP_NO_CACHE_DIR=1 \
+    PYTHONUNBUFFERED=1
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+        python3 python3-pip python3-dev \
+        libgl1 libglib2.0-0 \
+        git ca-certificates \
+    && rm -rf /var/lib/apt/lists/* \
+    && ln -sf /usr/bin/python3 /usr/bin/python
+
+WORKDIR /app
+
+COPY workers/colorize/requirements.txt .
+RUN pip3 install --upgrade pip && pip3 install -r requirements.txt
+# Install runpod LAST so modelscope's dependency pins can't break `import runpod`
+# at worker startup (the cause of "worker never becomes ready, no logs").
+RUN pip3 install runpod==1.7.9
+
+COPY workers/colorize/handler.py .
+
+CMD ["python3", "-u", "handler.py"]