Initial commit: Sudoku game with accounts, history, leaderboard, themes and i18n

Node/Express + SQLite backend, vanilla JS frontend, deployed via Docker Compose.

Dockerfile

@@ -0,0 +1,15 @@
+FROM node:22-bookworm-slim
+
+WORKDIR /app
+
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends python3 build-essential ca-certificates \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY server/package.json ./
+RUN npm install --omit=dev
+
+COPY server/ ./
+
+EXPOSE 3000
+CMD ["node", "server.js"]