fix(backup): install pg_dump (postgresql16-client) in app + worker images

The DR backup engine spawns `pg_dump` (backup.service.ts), but neither
runner image installed a postgres client — so producing a bundle fails
in prod with ENOENT (only worked in dev, where the host has pg_dump).
Surfaced by testing the feature on the live prod container.

Add `postgresql16-client` (pg_dump 16.x, matched to the postgres:16
server) to the runner stage of Dockerfile (crm-app: on-demand export +
"back up now") and Dockerfile.worker (scheduled backup-push cron).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Dockerfile.worker

@@ -26,6 +26,9 @@ FROM node:20-alpine AS runner
 RUN corepack enable && corepack prepare pnpm@10.33.2 --activate
 RUN addgroup --system --gid 1001 nodejs && adduser --system --uid 1001 worker
 WORKDIR /app
+# pg_dump for the scheduled backup-push cron (maintenance worker runs
+# runScheduledBackupPush → pg_dump). Pinned to match the postgres:16 server.
+RUN apk add --no-cache postgresql16-client
 RUN chown -R worker:nodejs /app
 USER worker
 COPY --chown=worker:nodejs package.json pnpm-lock.yaml ./