Fix AWK-UNINIT issues by initializing variables in BEGIN blocks

lib/php-analyzer.sh:
- Line 364: Initialize sum=0 in awk for request counting
- Line 1374: Initialize sum=0 in awk for MySQL memory calculation

modules/diagnostics/loadwatch-analyzer.sh:
- Lines 748-752: Initialize i=0 for memory velocity parsing
- Lines 794-797: Initialize i=0 for load trend parsing

modules/performance/hardware-health-check.sh:
- Lines 1243, 1244, 1247: Initialize sum=0 for network error metrics

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

lib/php-analyzer.sh

@@ -361,7 +361,7 @@ calculate_avg_requests_per_minute() {
 
     # Count total requests in last N hours
     local total_requests
-    total_requests=$(find "$access_logs" -mmin -$((hours * 60)) -exec wc -l {} \; 2>/dev/null | awk '{sum+=$1} END {print sum}')
+    total_requests=$(find "$access_logs" -mmin -$((hours * 60)) -exec wc -l {} \; 2>/dev/null | awk 'BEGIN {sum=0} {sum+=$1} END {print sum}')
 
     if [ -z "$total_requests" ] || [ "$total_requests" -eq 0 ]; then
         echo "0|No recent requests"
@@ -1371,7 +1371,7 @@ detect_mysql_memory_usage() {
 
     # Try to get actual memory usage from ps
     local mysql_rss_kb
-    mysql_rss_kb=$(ps aux | grep -E "[m]ysqld|[m]ariadbd" | awk '{sum+=$6} END {print sum}')
+    mysql_rss_kb=$(ps aux | grep -E "[m]ysqld|[m]ariadbd" | awk 'BEGIN {sum=0} {sum+=$6} END {print sum}')
 
     if [ -n "$mysql_rss_kb" ] && [ "$mysql_rss_kb" -gt 0 ]; then
         local mysql_rss_mb=$((mysql_rss_kb / 1024))