Fix TYPE-MISMATCH issues in email diagnostic scripts

modules/email/email-diagnostics.sh:
- Quote account_found variable in comparisons (lines 374, 378)

modules/email/deliverability-test.sh:
- Quote listed variable in comparison (line 166)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

modules/email/deliverability-test.sh

@@ -163,7 +163,7 @@ else
         fi
     done
 
-    if [ $listed -gt 0 ]; then
+    if [ "$listed" -gt 0 ]; then
         echo ""
         print_warning "  ⚠ Your IP is listed on $listed blacklist(s)"
         echo "    Recommendation: Use blacklist-check tool for delisting options"

modules/email/email-diagnostics.sh

@@ -371,11 +371,11 @@ if [ "$check_type" != "2" ]; then
     fi
 
     # If successful logins exist, account must exist (even if we can't find the directory)
-    if [ $account_found -eq 0 ] && [ "$auth_success" -gt 0 ]; then
+    if [ "$account_found" -eq 0 ] && [ "$auth_success" -gt 0 ]; then
         account_found=1
         print_success "Email account EXISTS (confirmed by successful logins)"
         print_warning "Note: Mailbox directory not found in standard locations"
-    elif [ $account_found -eq 1 ]; then
+    elif [ "$account_found" -eq 1 ]; then
         print_success "Email account EXISTS on this server"
 
         # Show mailbox details if we found the directory