Fix npm installation issues during setup

- Created reusable ensure_npm_packages function for consistency
- Fixed npm install being called in wrong directory during installation
- Added proper directory context preservation for npm operations
- Ensured package.json file is always copied to installation directory
- Added checks to prevent redundant npm installations
- Improved error handling and reporting for npm operations

🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>

main-installer.sh

@@ -295,10 +295,8 @@ EOF
     exit 1
   }
   
-  # Install npm dependencies
-  log "INFO" "Updating npm dependencies..."
-  cd "$SCRIPT_DIR"
-  npm install || {
+  # Install npm dependencies using our common function
+  ensure_npm_packages "$INSTALL_DIR" || {
     log "ERROR" "NPM installation failed"
     exit 1
   }
@@ -393,10 +391,8 @@ else
     exit 1
   }
   
-  # Step 6: Install npm dependencies
-  log "INFO" "Installing npm dependencies..."
-  cd "$SCRIPT_DIR"
-  npm install || {
+  # Step 6: Install npm dependencies using our common function
+  ensure_npm_packages "$INSTALL_DIR" || {
     log "ERROR" "NPM installation failed"
     exit 1
   }