feat(frontend): restyle monitoring charts on the Beszel school

Ports Beszel's chart design language onto our recharts primitives:
titled card grid, area fills on a true time axis, unit-aware Y ticks,
sorted dotted tooltips, and legend chips. System detail gains stacked
per-container Docker CPU/memory, per-sensor temperature lines, load
1/5/15, and GPU usage/VRAM — all from data the agent already sends.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/frontend/src/pages/SystemsPage.tsx

@@ -15,11 +15,14 @@ import { t } from "@/i18n";
 const TB = 2 ** 40;
 const GB = 2 ** 30;
 const MB = 2 ** 20;
+const KB = 2 ** 10;
 
 export function fmtBytes(b: number) {
 	if (b >= TB) return `${(b / TB).toFixed(1)} TB`;
 	if (b >= GB) return `${(b / GB).toFixed(1)} GB`;
-	return `${(b / MB).toFixed(0)} MB`;
+	if (b >= MB) return `${(b / MB).toFixed(1)} MB`;
+	if (b >= KB) return `${(b / KB).toFixed(0)} KB`;
+	return `${Math.round(b)} B`;
 }
 
 export function fmtUptime(s: number) {