Fix integer expression errors in php-analyzer.sh

Problem:
- Lines 435, 447, 457: integer expression expected errors
- convert_to_bytes() returns empty string when input is empty
- Bash arithmetic fails on empty strings: [ "" -lt 128 ]

Fix:
- Added empty checks before all numeric comparisons
- Pattern: [ -n "$var" ] && [ "$var" -lt value ]
- Applied to lines 435, 447, 457

Lines fixed:
- 435: post_bytes vs upload_bytes comparison
- 447: memory_bytes vs 128MB comparison
- 457: error_count > 0 comparison

Result:
- No more integer expression errors
- Script completes domain analysis successfully

lib/php-analyzer.sh

@@ -432,7 +432,7 @@ detect_php_config_issues() {
     post_bytes=$(convert_to_bytes "$post_max")
 
     # ISSUE 1: post_max_size < upload_max_filesize
-    if [ "$post_bytes" -lt "$upload_bytes" ]; then
+    if [ -n "$post_bytes" ] && [ -n "$upload_bytes" ] && [ "$post_bytes" -lt "$upload_bytes" ]; then
         issues+="CONFIG_MISMATCH|CRITICAL|post_max_size ($post_max) < upload_max_filesize ($upload_max)|Set post_max_size >= upload_max_filesize"$'\n'
     fi
 
@@ -444,7 +444,7 @@ detect_php_config_issues() {
     # ISSUE 3: memory_limit too low
     local memory_bytes
     memory_bytes=$(convert_to_bytes "$memory_limit")
-    if [ "$memory_bytes" -lt $((128 * 1024 * 1024)) ]; then
+    if [ -n "$memory_bytes" ] && [ "$memory_bytes" -lt $((128 * 1024 * 1024)) ]; then
         issues+="PERFORMANCE|MEDIUM|memory_limit is very low ($memory_limit)|Consider increasing to at least 128M"$'\n'
     fi
 
@@ -454,7 +454,7 @@ detect_php_config_issues() {
     local error_count
     error_count=$(echo "$max_children_errors" | grep "TOTAL" | cut -d'|' -f1)
 
-    if [ "$error_count" -gt 0 ]; then
+    if [ -n "$error_count" ] && [ "$error_count" -gt 0 ]; then
         issues+="CAPACITY|CRITICAL|pm.max_children limit reached $error_count times in last 7 days|Increase pm.max_children setting"$'\n'
     fi