Fix NULL check issues (HIGH priority)

Added validation checks for potentially empty variables before use
to prevent errors and unsafe operations.

WordPress Cron Manager (5 fixes):
- Added site_path validation after dirname operations
- Prevents using empty paths in cd commands and file operations
- Pattern: Check [ -z "$site_path" ] before use

Bot Analyzer:
- Quoted TEMP_DIR in trap command for safety

Hardware Health Check:
- Quoted MESSAGES_CACHE in trap command for safety

Note: 5 issues flagged in toolkit-qa-check.sh were false positives
(echo statements demonstrating bad patterns, not actual code issues)

modules/performance/hardware-health-check.sh

@@ -1700,7 +1700,7 @@ main() {
         touch "$MESSAGES_CACHE"
     fi
     # Cleanup cache on exit
-    trap "rm -f $MESSAGES_CACHE" EXIT
+    trap "rm -f \"$MESSAGES_CACHE\"" EXIT
 
     # Run diagnostics with progress indicators
     echo -e "${YELLOW}[1/11]${NC} Analyzing disk SMART status and predictive failure indicators..."

modules/security/bot-analyzer.sh

@@ -240,7 +240,7 @@ mkdir -p "$TEMP_DIR" || {
 }
 
 # Cleanup on exit
-trap "rm -rf $TEMP_DIR" EXIT
+trap "rm -rf \"$TEMP_DIR\"" EXIT
 
 #############################################################################
 # Bot Signature Database

modules/website/wordpress/wordpress-cron-manager.sh

@@ -379,6 +379,10 @@ case "$choice" in
 
         # Add cron job with staggered timing
         site_path=$(dirname "$wp_config")
+        if [ -z "$site_path" ]; then
+            echo -e "${RED}✗${NC} Could not determine site path"
+            continue
+        fi
         cron_cmd="cd $site_path && /usr/bin/php -q wp-cron.php >/dev/null 2>&1"
 
         # Add to user's crontab - Multi-panel support
@@ -522,6 +526,10 @@ case "$choice" in
         while IFS= read -r wp_config; do
             total=$((total + 1))
             site_path=$(dirname "$wp_config")
+            if [ -z "$site_path" ]; then
+                echo -e "${RED}✗ Could not determine site path${NC}"
+                continue
+            fi
             user=$(extract_user_from_path "$site_path")
 
             echo -e "${BOLD}Processing:${NC} $site_path (user: $user)"
@@ -898,6 +906,10 @@ case "$choice" in
         while IFS= read -r wp_config; do
             total=$((total + 1))
             site_path=$(dirname "$wp_config")
+            if [ -z "$site_path" ]; then
+                echo -e "${RED}✗ Could not determine site path${NC}"
+                continue
+            fi
             user=$(extract_user_from_path "$site_path")
 
             echo -e "${BOLD}Processing:${NC} $site_path (user: $user)"