ci: Consolidate back to 4 docker steps

- Remove separate build steps (didn't save time)
- Use original multi-stage Dockerfiles
- Delete unused Dockerfile.ci files
- 4 parallel docker builds + deploy

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

findagram/frontend/Dockerfile.ci

@@ -1,25 +0,0 @@
-# CI Dockerfile - assets pre-built in CI step
-FROM nginx:alpine
-
-# Copy pre-built assets from CI (CRA builds to /build)
-COPY findagram/frontend/build /usr/share/nginx/html
-
-# SPA routing config
-RUN echo 'server { \
-    listen 80; \
-    server_name _; \
-    root /usr/share/nginx/html; \
-    index index.html; \
-    gzip on; \
-    gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript; \
-    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ { \
-        expires 1y; \
-        add_header Cache-Control "public, immutable"; \
-    } \
-    location / { \
-        try_files $uri $uri/ /index.html; \
-    } \
-}' > /etc/nginx/conf.d/default.conf
-
-EXPOSE 80
-CMD ["nginx", "-g", "daemon off;"]