remove legacy backend stack and stale deployment docs after rebuild

frontend/Dockerfile

@@ -2,25 +2,22 @@ FROM node:20-alpine AS base
 
 WORKDIR /app
 
-# Install dependencies
 FROM base AS deps
 COPY package.json ./
 RUN npm install
 
-# Build
 FROM base AS builder
-ARG NEXT_PUBLIC_API_URL=http://backend:3001
+ARG NEXT_PUBLIC_API_URL=
 ENV NEXT_PUBLIC_API_URL=${NEXT_PUBLIC_API_URL}
 COPY --from=deps /app/node_modules ./node_modules
 COPY . .
 RUN mkdir -p public && npm run build
 
-# Production
 FROM base AS runner
 WORKDIR /app
 
 ENV NODE_ENV=production
-ARG NEXT_PUBLIC_API_URL=http://backend:3001
+ARG NEXT_PUBLIC_API_URL=
 ENV NEXT_PUBLIC_API_URL=${NEXT_PUBLIC_API_URL}
 
 RUN addgroup --system --gid 1001 nodejs