chore: Optimize Dockerfile for improved build performance and update Gitea workflows with Docker Buildx support

Dockerfile.fast

@@ -0,0 +1,45 @@
+# Stage 1: Build React frontend
+FROM node:20-alpine AS frontend-builder
+WORKDIR /app/frontend
+
+# Install yarn for faster package management
+RUN npm install -g yarn
+
+# Copy package files
+COPY frontend/package*.json ./
+COPY frontend/yarn.lock* ./
+
+# Install dependencies with yarn (faster than npm)
+RUN yarn install --frozen-lockfile --network-timeout 300000
+
+# Copy source code
+COPY frontend/ .
+
+# Build the application
+RUN yarn build
+
+# Stage 2: Setup Node.js backend and serve everything
+FROM node:20-alpine
+WORKDIR /app
+
+# Install yarn for faster package management
+RUN npm install -g yarn
+
+# Copy package files
+COPY backend/package*.json ./
+COPY backend/yarn.lock* ./
+
+# Install production dependencies only
+RUN yarn install --frozen-lockfile --production --network-timeout 300000
+
+# Copy backend source code
+COPY backend/ .
+
+# Copy built frontend assets from the previous stage
+COPY --from=frontend-builder /app/frontend/dist ./public
+
+# The port the backend runs on
+EXPOSE 3001
+
+# Start the server
+CMD ["node", "server.js"]