CRITICAL FIX: Protect all array variable accesses in threat scoring loop

Lines 1812-1850: Protected all array accesses with default guards
- header_score: Added ${header_score:-0} guards
- fuzz_requests: Added ${fuzz_requests:-0} guards
- admin_count: Changed from 2>/dev/null to ${admin_count:-0} guards
- scan_404: Changed from 2>/dev/null to ${scan_404:-0} guards

These were causing type mismatches when array values were undefined.
This was the root cause of script exit after 'Calculating threat scores'.

modules/security/bot-analyzer.sh

@@ -1809,8 +1809,8 @@ calculate_threat_scores() {
 
         # NEW: Header anomalies (strong indicator of bots)
         if [ -n "${header_anomalies[$ip]}" ]; then
-            header_score=${header_anomalies[$ip]}
-            if [ "$header_score" -ge 12 ]; then
+            header_score=${header_anomalies[$ip]:-0}
+            if [ "${header_score:-0}" -ge 12 ]; then
                 score=$((score + 8))  # Multiple header suspicions
             elif [ "$header_score" -ge 8 ]; then
                 score=$((score + 5))  # Moderate header anomalies
@@ -1824,10 +1824,10 @@ calculate_threat_scores() {
 
         # NEW: Fuzzing/parameter scanning behavior
         if [ -n "${fuzzing_ips[$ip]}" ]; then
-            fuzz_requests=${fuzzing_ips[$ip]}
-            if [ "$fuzz_requests" -gt 100 ]; then
+            fuzz_requests=${fuzzing_ips[$ip]:-0}
+            if [ "${fuzz_requests:-0}" -gt 100 ]; then
                 score=$((score + 7))  # Aggressive fuzzing
-            elif [ "$fuzz_requests" -gt 50 ]; then
+            elif [ "${fuzz_requests:-0}" -gt 50 ]; then
                 score=$((score + 4))  # Moderate fuzzing
             fi
         fi
@@ -1839,15 +1839,15 @@ calculate_threat_scores() {
 
         # Admin probing - IMPROVED: Raised threshold to 50 (only failed attempts counted)
         admin_count=${threat_admin_count[$ip]:-0}
-        if [ "$admin_count" -gt 100 ] 2>/dev/null; then
+        if [ "${admin_count:-0}" -gt 100 ]; then
             score=$((score + 10))  # Excessive probing
-        elif [ "$admin_count" -gt 50 ] 2>/dev/null; then
+        elif [ "${admin_count:-0}" -gt 50 ]; then
             score=$((score + 5))   # Moderate probing
         fi
 
         # 404 scanning
         scan_404=${threat_404_count[$ip]:-0}
-        [ "$scan_404" -gt 50 ] 2>/dev/null && score=$((score + 3))
+        [ "${scan_404:-0}" -gt 50 ] && score=$((score + 3))
 
         # OPTIMIZATION: Skip external API calls for performance
         # Threat Intelligence Enrichment can be done post-analysis for high-risk IPs only