feat(frontend): revamp monitor cards and process table

Add a dedicated CPU history chart with per-core live indicators, switch the
network block to a vertical stack with a tighter height cap, and lift process
counts into header pills.

Also make the process list columns sortable, add spacing around the close
button, and extend backend CPU sampling to include per-core usage data.

packages/frontend/src/components/StatusMonitorNetworkHistoryChart.vue

@@ -259,22 +259,22 @@ onBeforeUnmount(() => {
 <style scoped>
 .network-history-chart {
   display: grid;
-  gap: 10px;
+  gap: 8px;
   min-width: 0;
-  height: 100%;
+  height: auto;
   border-radius: 16px;
   border: 1px solid rgba(148, 163, 184, 0.08);
   background:
     linear-gradient(180deg, rgba(255, 255, 255, 0.035), rgba(255, 255, 255, 0.02)),
     radial-gradient(circle at top left, rgba(59, 130, 246, 0.06), transparent 62%);
-  padding: 12px;
+  padding: 10px;
 }
 
 .network-history-chart__header {
   display: flex;
   align-items: flex-start;
   justify-content: space-between;
-  gap: 12px;
+  gap: 10px;
 }
 
 .network-history-chart__subtitle {
@@ -327,7 +327,7 @@ onBeforeUnmount(() => {
 .network-history-chart__canvas {
   min-width: 0;
   width: 100%;
-  height: 164px;
+  height: 108px;
   overflow: hidden;
 }