build: migrate CI and Docker setup to pnpm

Dockerfile

@@ -1,12 +1,17 @@
 # Base stage for building the static files
 FROM node:lts AS base
 WORKDIR /app
-COPY package*.json ./
-RUN npm install
+
+# Install pnpm
+RUN corepack enable && corepack prepare pnpm@latest --activate
+
+COPY package.json pnpm-lock.yaml ./
+RUN pnpm install --frozen-lockfile
+
 COPY . .
-RUN npm run build
+RUN pnpm run build
 
 # Runtime stage for serving the application
 FROM nginx:mainline-alpine-slim AS runtime
-COPY --from=base ./app/dist /usr/share/nginx/html
-EXPOSE 80
+COPY --from=base /app/dist /usr/share/nginx/html
+EXPOSE 80