refactor: restore root layout and split mysql config

Dockerfile

@@ -0,0 +1,16 @@
+FROM python:3.12-slim
+
+ENV PYTHONDONTWRITEBYTECODE=1 \
+    PYTHONUNBUFFERED=1
+
+WORKDIR /app
+
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends git ca-certificates default-mysql-client \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY . /app
+
+EXPOSE 8123
+
+CMD ["sh", "tools/container_start.sh"]