feat: Add help flag support to enhanced crontab management script installation

crontab-backup-system.sh

@@ -271,7 +271,7 @@ validate_crontab_syntax() {
     local errors=0
     
     while IFS= read -r line; do
-        ((line_num++))
+        line_num=$((line_num + 1))
         
         # Skip comments and empty lines
         if [[ "$line" =~ ^[[:space:]]*# ]] || [[ "$line" =~ ^[[:space:]]*$ ]]; then
@@ -279,9 +279,9 @@ validate_crontab_syntax() {
         fi
         
         # Basic cron format validation
-        if [[ ! "$line" =~ ^[[:space:]]*([0-9*,-]+[[:space:]]+){4}[0-9*,-]+[[:space:]].+ ]]; then
+        if ! [[ "$line" =~ ^[[:space:]]*([0-9*,-]+[[:space:]]+){4}[0-9*,-]+[[:space:]].+ ]]; then
             log_error "Line $line_num: Invalid cron format: $line"
-            ((errors++))
+            errors=$((errors + 1))
         fi
         
         # Check for common issues