Avoids Docker Hub 429 rate limits by pulling node:20-alpine and
nginx:stable-alpine from ghcr.io/cartsnitch/mirror/. GHCR login
now runs on all builds (not just main push) to authenticate pulls.
Ref: cartsnitch/infra#7, CAR-55
Co-Authored-By: Paperclip <noreply@paperclip.ing>
Build stage uses node:20-alpine to install deps and build.
Prod stage uses nginx:stable-alpine to serve static assets.
Includes nginx config with SPA routing, gzip, health endpoint,
and aggressive caching for Vite-hashed assets.
Closes#6
Co-Authored-By: Paperclip <noreply@paperclip.ing>