Fix Dockerfile for hoisted npm workspace dependencies

- Copy root node_modules instead of workspace-specific ones
- Add separate prod-deps stage for production dependencies only
- Set NODE_PATH to resolve modules from root in production
- Fixes 'node_modules not found' error in build

Author: mattburchett

Dockerfile

@@ -16,13 +16,12 @@ FROM node:20-alpine AS frontend-build
 
 WORKDIR /app
 
-# Copy dependencies from deps stage
+# Copy root node_modules (npm workspaces hoists dependencies)
 COPY --from=deps /app/node_modules ./node_modules
-COPY --from=deps /app/frontend/node_modules ./frontend/node_modules
 
-# Copy frontend source
+# Copy workspace packages and frontend source
+COPY --from=deps /app/package*.json ./
 COPY frontend/ ./frontend/
-COPY package*.json ./
 
 # Build frontend
 RUN npm run build:frontend
@@ -32,28 +31,42 @@ FROM node:20-alpine AS backend-build
 
 WORKDIR /app
 
-# Copy dependencies from deps stage
+# Copy root node_modules (npm workspaces hoists dependencies)
 COPY --from=deps /app/node_modules ./node_modules
-COPY --from=deps /app/backend/node_modules ./backend/node_modules
 
-# Copy backend source
+# Copy workspace packages and backend source
+COPY --from=deps /app/package*.json ./
 COPY backend/ ./backend/
-COPY package*.json ./
 
 # Build backend
 RUN npm run build:backend
 
-# Stage 4: Production
+# Stage 4: Production - Install only production dependencies
+FROM node:20-alpine AS prod-deps
+
+WORKDIR /app
+
+# Copy workspace package files
+COPY package*.json ./
+COPY backend/package*.json ./backend/
+COPY frontend/package*.json ./frontend/
+
+# Install only production dependencies
+RUN npm ci --omit=dev
+
+# Stage 5: Final production image
 FROM node:20-alpine
 
 WORKDIR /app
 
 # Install runtime dependencies
 RUN apk add --no-cache nginx supervisor
 
+# Copy production node_modules
+COPY --from=prod-deps /app/node_modules ./node_modules
+
 # Copy built backend
 COPY --from=backend-build /app/backend/dist ./backend/dist
-COPY --from=backend-build /app/backend/node_modules ./backend/node_modules
 COPY --from=backend-build /app/backend/package.json ./backend/
 
 # Copy built frontend
@@ -92,7 +105,7 @@ stdout_logfile_maxbytes=0
 stderr_logfile=/dev/stderr
 stderr_logfile_maxbytes=0
 directory=/app/backend
-environment=NODE_ENV=production
+environment=NODE_ENV=production,NODE_PATH=/app/node_modules
 EOF
 
 EXPOSE 80