Add more debugging for backend npm install

- Explicitly create backend directory
- Show full npm install output
- Add explicit error message on failure

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

Dockerfile

@@ -2,11 +2,14 @@ FROM node:20-slim
 
 ENV DEBIAN_FRONTEND=noninteractive
 
-# Build timestamp: 2026-01-13T00:00
+# Build timestamp: 2026-01-13T00:10
 
 # Minimal test - just check if files exist
 WORKDIR /app
 
+# Create directories explicitly
+RUN mkdir -p backend
+
 # Test COPY commands one by one
 RUN echo "Step 1: Working directory set"
 
@@ -14,19 +17,22 @@ COPY trigo-web/package.json ./package.json
 RUN echo "Step 2: Root package.json copied" && cat package.json | head -5
 
 COPY trigo-web/backend/package.json ./backend/package.json
-RUN echo "Step 3: Backend package.json copied" && cat backend/package.json | head -5
+RUN echo "Step 3: Backend package.json copied" && ls -la backend/ && cat backend/package.json | head -10
 
 # Install only esbuild (smaller than yarn)
 RUN npm install -g esbuild
 RUN echo "Step 4: esbuild installed"
 
-# Install root deps
-RUN npm install --omit=dev --legacy-peer-deps
+# Install root deps - this is simple, only dotenv
+RUN npm install --omit=dev
 RUN echo "Step 5: Root deps installed"
 
-# Install backend deps
-RUN cd backend && npm install --omit=dev --legacy-peer-deps
-RUN echo "Step 6: Backend deps installed"
+# Install backend deps - show full output
+RUN echo "Step 6: Starting backend npm install..." && \
+    cd backend && \
+    npm install --omit=dev 2>&1 && \
+    echo "Step 6: Backend deps installed successfully" || \
+    (echo "Step 6: Backend npm install FAILED" && exit 1)
 
 # Copy backend source
 COPY trigo-web/backend/src/ ./backend/src/