Fix: Add .npmrc config and improve npm install robustness

.npmrc

@@ -0,0 +1,5 @@
+legacy-peer-deps=true
+audit=false
+fund=false
+progress=false
+omit=dev

Dockerfile

@@ -2,13 +2,17 @@ FROM node:18-alpine
 
 WORKDIR /app
 
+# Copy npm config first
+COPY .npmrc ./
+
 # Copy package files
 COPY backend/package*.json ./
 
-# Install dependencies - bypass npm bugs
-RUN npm ci --omit=dev || npm install --omit=dev || true && \
-    npm install --save express express-session bcryptjs dotenv cors multer fs-extra && \
-    if [ ! -d node_modules/express ]; then echo "ERROR: express not installed" && exit 1; fi
+# Install dependencies with retry logic
+RUN npm cache clean --force && \
+    npm install --no-optional --legacy-peer-deps 2>&1 | tail -20 && \
+    ls -la node_modules/express || npm install express && \
+    test -d node_modules/express || (echo "FATAL: express not found" && exit 1)
 
 # Copy application code
 COPY backend/src ./src