Fix menu standards: Replace plain dashes with Unicode separators

Replaced all plain dash separators (---) with Unicode (───) for consistency:

Fixed lib/common-functions.sh (1):
- print_section(): 79 dashes → 79 unicode dashes

Fixed lib/user-manager.sh (4):
- All occurrences: 79 dashes → 79 unicode dashes (replace_all)

Fixed modules/performance/php-optimizer.sh (1):
- Table separator: 104 dashes → 104 unicode dashes

Fixed modules/security/malware-scanner.sh (4):
- All occurrences: 40 dashes → 40 unicode dashes (replace_all)

All 8/8 separator issues resolved. Menus now have consistent Unicode styling.

lib/user-manager.sh

@@ -429,7 +429,7 @@ select_user_interactive() {
         print_section "$prompt"
         echo ""
         echo "Found $total_users user(s) on this server"
-        echo "-------------------------------------------------------------------------------"
+        echo "───────────────────────────────────────────────────────────────────────────────"
 
         # Auto-show list if 10 or fewer users
         if [ "${total_users:-0}" -le 10 ]; then
@@ -440,7 +440,7 @@ select_user_interactive() {
         fi
 
         echo ""
-        echo "-------------------------------------------------------------------------------"
+        echo "───────────────────────────────────────────────────────────────────────────────"
         echo ""
         echo "Options:"
         if [ "${total_users:-0}" -gt 10 ]; then
@@ -531,11 +531,11 @@ select_user_interactive() {
             {
                 echo ""
                 echo "Complete user list ($total_users users):"
-                echo "-------------------------------------------------------------------------------"
+                echo "───────────────────────────────────────────────────────────────────────────────"
                 for user in "${users[@]}"; do
                     echo -e "  ${GREEN}$user${NC} - ${user_primary_domain[$user]} (${user_domain_count[$user]} domains)"
                 done
-                echo "-------------------------------------------------------------------------------"
+                echo "───────────────────────────────────────────────────────────────────────────────"
                 echo ""
             } >&2
             # Ask again after showing list