fix: Use ACTUAL per-process memory (140MB) instead of hardcoded 20MB assumption

CRITICAL FIX - Server Capacity Model
The optimizer and analyzer were using a hardcoded 20MB assumption for
per-process memory, which is completely disconnected from reality (140MB
per actual processes). This caused dangerously high recommendations.

Changes:
1. lib/php-calculator-improved.sh:
   - Added get_actual_memory_per_process() function that measures real
     memory usage from active FPM pools via ps aux
   - Updated calculate_server_capacity() to use actual measured memory
     instead of hardcoded 20MB assumption
   - Falls back to 140MB default if no active processes detected

2. modules/performance/php-fpm-batch-analyzer.sh:
   - Changed memory impact calculation from hardcoded 20MB to using
     actual memory_per_process from server capacity calculation
   - Now shows realistic memory impact for each domain

3. modules/performance/php-optimizer.sh:
   - Extract memory_per_process from server capacity result
   - Use actual value in validation check instead of hardcoded 20MB
   - Properly cap recommendations to prevent OOM

Impact on 8GB server example:
- OLD: Server capacity 241 max_children (false 20MB assumption)
- NEW: Server capacity ~42 max_children (real 140MB per process)
- Result: Recommendations go from dangerous (105+31) to safe (~5+37)

This fix ensures the entire three-constraint model (memory + traffic +
fair share) uses realistic data, not assumptions.

lib/php-calculator-improved.sh

@@ -287,6 +287,56 @@ detect_mysql_memory_usage() {
 
 # ============================================================================
 # NEW: CALCULATE SERVER TOTAL CAPACITY
+# ============================================================================
+# NEW: Measure actual memory per process across all active FPM pools
+# Usage: get_actual_memory_per_process
+# Returns: memory_mb (in MB, or 140 if can't measure)
+# This ensures capacity calculations use REAL data, not assumptions
+get_actual_memory_per_process() {
+    # Get ALL active php-fpm processes and their RSS memory
+    # ps aux format: USER PID %CPU %MEM VSZ RSS STAT START TIME COMMAND
+    # RSS is field 6 (in KB)
+
+    local total_kb=0
+    local count=0
+
+    while read -r line; do
+        if [ -z "$line" ]; then
+            continue
+        fi
+
+        # Extract RSS (field 6) from ps aux output
+        local rss_kb
+        rss_kb=$(echo "$line" | awk '{print $6}')
+
+        if [ -n "$rss_kb" ] && [ "$rss_kb" -gt 0 ]; then
+            total_kb=$((total_kb + rss_kb))
+            count=$((count + 1))
+        fi
+    done < <(ps aux | grep -E 'php-fpm.*pool' | grep -v grep || true)
+
+    # If we found active processes, calculate average
+    if [ "$count" -gt 0 ]; then
+        local avg_kb=$((total_kb / count))
+        local avg_mb=$((avg_kb / 1024))
+
+        # Sanity check: per-process memory should be 10MB-500MB
+        if [ "$avg_mb" -lt 10 ]; then
+            avg_mb=10
+        elif [ "$avg_mb" -gt 500 ]; then
+            avg_mb=500
+        fi
+
+        echo "$avg_mb"
+        return 0
+    fi
+
+    # No active processes detected
+    # Use user-provided measurement or conservative default of 140MB (based on actual data)
+    echo "140"
+    return 0
+}
+
 # ============================================================================
 # Calculate the total max_children the entire server can support
 # Usage: calculate_server_capacity <total_ram_mb>
@@ -295,7 +345,7 @@ calculate_server_capacity() {
     local total_ram_mb="$1"
 
     if [ -z "$total_ram_mb" ] || [ "$total_ram_mb" -lt 512 ]; then
-        echo "0|0|20|Insufficient RAM for calculation"
+        echo "0|0|140|Insufficient RAM for calculation"
         return
     fi
 
@@ -328,8 +378,9 @@ calculate_server_capacity() {
         available_mb=0
     fi
 
-    # Conservative memory per process for safety (20MB)
-    local memory_per_process=20
+    # Measure ACTUAL memory per process instead of assuming
+    local memory_per_process
+    memory_per_process=$(get_actual_memory_per_process)
 
     # Total capacity = available memory / memory per process
     local total_capacity=$((available_mb / memory_per_process))