fix: use npm install instead of npm ci in scheduler Dockerfile

npm ci requires a package-lock.json which is not present.

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

infrastructure/scheduler/Dockerfile

@@ -1,7 +1,7 @@
 FROM node:22-alpine
 WORKDIR /app
 COPY package*.json ./
-RUN npm ci --omit=dev
+RUN npm install --omit=dev
 COPY src ./src
 # APNs-Zertifikat-Verzeichnis (optional)
 RUN mkdir -p /app/certs