ci(docker): add production dockerfile, compose config, and gitea actions pipeline

Dockerfile

@@ -0,0 +1,38 @@
+# Multi-stage lightweight Docker image for Fridger
+FROM node:22-alpine AS runner
+
+# Create app directory
+WORKDIR /app
+
+# Set environment
+ENV NODE_ENV=production \
+    PORT=3000 \
+    FRIDGER_DATA_DIR=/data \
+    FRIDGER_DB_PATH=/data/fridger.db
+
+# Install dependencies first for layer caching
+COPY package.json package-lock.json ./
+RUN npm ci --omit=dev && npm cache clean --force
+
+# Copy application source
+COPY server.js db.js barcode.js ./
+COPY public/ ./public/
+
+# Setup persistent data storage directory with proper permissions
+RUN mkdir -p /data && chown -R node:node /app /data
+
+# Use non-root user
+USER node
+
+# Expose web port
+EXPOSE 3000
+
+# Declare persistent volume
+VOLUME ["/data"]
+
+# Health check
+HEALTHCHECK --interval=30s --timeout=5s --start-period=5s --retries=3 \
+  CMD wget --no-verbose --tries=1 --spider http://localhost:3000/health || exit 1
+
+# Start the application
+CMD ["node", "server.js"]