fix(docker): Use mirror.gcr.io in all Dockerfiles to avoid rate limits

backend/Dockerfile

@@ -1,6 +1,6 @@
 # Build stage
 # Image: git.spdy.io/creationshop/dispensary-scraper
-FROM node:20-slim AS builder
+FROM mirror.gcr.io/library/node:22-slim AS builder
 
 # Install build tools for native modules (bcrypt, sharp)
 RUN apt-get update && apt-get install -y \
@@ -27,7 +27,7 @@ RUN npm run build
 RUN npm prune --production
 
 # Production stage
-FROM node:20-slim
+FROM mirror.gcr.io/library/node:22-slim
 
 # Build arguments for version info
 ARG APP_BUILD_VERSION=dev