fix: docker build - use root context for monorepo workspaces

- Change build context from ./frontend|backend to root (.)
- Update Dockerfiles to copy from correct paths
- Use npm install instead of npm ci (workspaces share root lockfile)
- Remove obsolete version attribute from docker-compose.yml

Fixes npm ci errors when package-lock.json is at workspace root.

backend/Dockerfile

@@ -3,20 +3,20 @@ FROM node:20-alpine AS builder
 
 WORKDIR /app
 
-# Copy package files
+# Copy root package files for workspace install
 COPY package*.json ./
-COPY prisma ./prisma/
+COPY backend/package*.json ./backend/
+COPY backend/prisma ./backend/prisma/
 
-# Install dependencies
-RUN npm ci
+# Install dependencies using npm install (no individual lockfile in workspace)
+RUN npm install --legacy-peer-deps
 
-# Copy source code
-COPY . .
+# Copy backend source
+COPY backend/ ./backend/
 
-# Generate Prisma client
+# Generate Prisma client and build
+WORKDIR /app/backend
 RUN npx prisma generate
-
-# Build TypeScript
 RUN npm run build
 
 # Production stage
@@ -29,14 +29,17 @@ RUN apk add --no-cache openssl
 
 # Copy package files
 COPY package*.json ./
+COPY backend/package*.json ./backend/
 
-# Install production dependencies only
-RUN npm ci --only=production
+# Install production dependencies
+RUN npm install --legacy-peer-deps --omit=dev
 
 # Copy built files from builder
-COPY --from=builder /app/dist ./dist
-COPY --from=builder /app/node_modules/.prisma ./node_modules/.prisma
-COPY --from=builder /app/prisma ./prisma
+COPY --from=builder /app/backend/dist ./backend/dist
+COPY --from=builder /app/backend/node_modules/.prisma ./backend/node_modules/.prisma
+COPY --from=builder /app/backend/prisma ./backend/prisma
+
+WORKDIR /app/backend
 
 # Expose port
 EXPOSE 3001