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.

.helloagents/archive/2026-04/202604190358_status-monitor-network-vertical-stack/.status.json

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+{"status":"completed","completed":4,"failed":0,"pending":0,"total":4,"done":4,"percent":100,"current":"网络模块上下堆叠与 350px 高度约束已完成，待归档方案包","updated_at":"2026-04-19 04:04:00"}