docs: add DOCKER_GUIDE.md and fix .env parsing; chore: update docker and script configurations

docker/Dockerfile.collector

@@ -0,0 +1,21 @@
+FROM python:3.11-slim
+
+WORKDIR /app
+
+# Copy requirements first (for better caching)
+COPY requirements.txt .
+
+# Install Python dependencies
+# --no-cache-dir reduces image size
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Copy application code
+COPY src/ ./src/
+COPY config/ ./config/
+COPY scripts/ ./scripts/
+
+# Set Python path
+ENV PYTHONPATH=/app
+
+# Run the collector
+CMD ["python", "-m", "src.data_collector.main"]