Update Dockerfile

Taipei-City-Dashboard-FE/Dockerfile

@@ -1,9 +1,21 @@
-FROM node:20.11.1-alpine3.19
+# Use the official lightweight Node.js 18 image.
+# https://hub.docker.com/_/node
+FROM node:19-alpine
 
-WORKDIR /opt/aipei-City-Dashboard-FE
+# Create and change to the app directory.
+WORKDIR /usr/src/app
 
-COPY ./ ./
+# Copy application dependency manifests to the container image.
+# A wildcard is used to ensure both package.json AND package-lock.json are copied.
+# Copying this separately prevents re-running npm install on every code change.
+COPY package*.json ./
 
+# Install dependencies.
+# If you add a package-lock.json speed your build by switching to 'npm ci'.
 RUN npm install
 
-CMD ["npm", "start"]
+# Copy local code to the container image.
+COPY . ./
+
+# Run the web service on container startup.
+CMD ["npm", "run", "dev"]