Improve Node.js setup for Debian systems

Enhances the setup_nodejs function to remove Debian-packaged Node.js if present, set APT preferences to prioritize NodeSource packages, and verify npm availability after installation. These changes help avoid conflicts between Debian and NodeSource Node.js versions and ensure npm is properly installed.

misc/tools.func

@@ -3321,6 +3321,13 @@ function setup_nodejs() {
     # Clean up legacy installations (nvm, etc.)
     cleanup_legacy_install "nodejs"
 
+    # Remove Debian's nodejs if present (conflicts with NodeSource)
+    if dpkg -l | grep -q "^ii.*nodejs.*dfsg"; then
+      $STD msg_info "Removing Debian-packaged Node.js (conflicts with NodeSource)"
+      $STD apt purge -y nodejs libnode* 2>/dev/null || true
+      $STD apt autoremove -y 2>/dev/null || true
+    fi
+
     ensure_dependencies curl ca-certificates gnupg
 
     # Prepare repository (cleanup + validation)
@@ -3335,10 +3342,21 @@ function setup_nodejs() {
       return 1
     }
 
+    # Set APT priority to prefer NodeSource over Debian repos
+    cat >/etc/apt/preferences.d/nodesource <<'EOF'
+Package: nodejs
+Pin: origin deb.nodesource.com
+Pin-Priority: 600
+
+Package: *
+Pin: origin deb.nodesource.com
+Pin-Priority: 600
+EOF
+
     # Wait for repo to settle
     sleep 2
 
-    # Install Node.js with retry logic
+    # Install Node.js with retry logic (explicit version to avoid Debian repo)
     install_packages_with_retry "nodejs" || {
       msg_error "Failed to install Node.js ${NODE_VERSION} from NodeSource"
       return 1
@@ -3354,6 +3372,12 @@ function setup_nodejs() {
     INSTALLED_NODE_VERSION=$(node -v 2>/dev/null | grep -oP '^v\K[0-9]+' || echo "0")
     verify_tool_version "Node.js" "$NODE_VERSION" "$INSTALLED_NODE_VERSION" || true
 
+    # Verify npm is available (should come with NodeSource nodejs)
+    if ! command -v npm >/dev/null 2>&1; then
+      msg_error "npm not found after Node.js installation - repository issue?"
+      return 1
+    fi
+
     # Update to latest npm (with version check to avoid incompatibility)
     local NPM_VERSION
     NPM_VERSION=$(npm -v 2>/dev/null || echo "0")