fix: use npm install and explicit package-lock.json COPY in sync Dockerfile

Avoids stale Docker layer cache issue where tsc was not found because
an old npm ci layer (without dev deps) was cached on the build host.

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

sync/Dockerfile

@@ -1,8 +1,8 @@
 # Stage 1: build TypeScript + install all deps
 FROM node:20-slim AS builder
 WORKDIR /app
-COPY package*.json ./
-RUN npm ci --include=dev
+COPY package.json package-lock.json ./
+RUN npm install
 COPY tsconfig.json ./
 COPY src ./src
 RUN ./node_modules/.bin/tsc && npm prune --production
@@ -15,3 +15,4 @@ COPY --from=builder /app/node_modules ./node_modules
 COPY --from=builder /app/dist ./dist
 
 CMD ["node", "dist/index.js"]
+