feat: implement PSS (Proportional Set Size) for accurate real memory tracking

src/App.tsx

@@ -580,8 +580,8 @@ function ReportView({ report, onBack }: { report: ProfilingReport, onBack: () =>
           </div>
 
           <div className="p-4 bg-surface0/50 border-t border-surface1 text-[9px] text-overlay1 font-medium italic flex items-center gap-2">
-            <AlertTriangle size={10} />
-            <span>Memory is Resident Set Size (RSS). Summed totals may exceed physical RAM due to shared segments.</span>
+            <Shield size={10} className="text-blue" />
+            <span>Memory is Proportional Set Size (PSS). It includes private memory plus a proportional share of shared libraries, providing an accurate sum of total system impact.</span>
           </div>
         </div>