Fix build stage: use npm install instead of npm ci

npm ci fails when the lockfile was generated on a different platform
or npm version than what runs inside the container. npm install is
more forgiving and resolves the exit code 1 in the build stage.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Dockerfile

@@ -1,7 +1,7 @@
 FROM node:22-alpine AS build
 WORKDIR /app
 COPY package*.json ./
-RUN npm ci
+RUN npm install
 COPY . .
 RUN npm run build