feat(ui): redesign the overview page as a trend-first command deck

Replace the ten-small-cards overview with an action bar, four vitals
tiles carrying 72-sample sparklines seeded from /server/history, a
two-series throughput chart, a TCP/UDP connections chart, and a
grouped system strip (uptime xray|os, panel ram|threads, ip
addresses). StatusCard and XrayStatusCard are deleted; every modal
stays reachable from the action bar, the Xray error message moves
into a tooltip on the state pill, and the panel version text keeps
opening the update modal (the dev-channel switch lives there) even
when no update is available. Live values sit beside the
upload/download and tcp/udp legends, a health sentence appears only
when a vital crosses the shared warn/crit thresholds now exported
from models/status, and load average is left to System History.

The sidebar becomes an auto-collapsed 72px icon rail that expands as
an overlay on hover: rail width, brand-row height and menu paddings
are pinned so nothing shifts during the transition, the collapsed-menu
tooltips are disabled, hover state survives the per-page sidebar
remounts (with a matches(':hover') resync), and the manual collapse
trigger is gone.

Sparkline gains rgb()/rgba() support in its fill gradient, a
showLegend prop so pages stop reaching into its internals, and loses
a dependency-less repaint effect that doubled canvas paints. Chart
tooltips show clock time via the new TimeFormatter.formatClock;
accents come from theme tokens instead of status.cpu.color. Verified
by screenshot at 390/800/1150/1280/1400/1600px in light and dark,
en and fa-IR, plus programmatic geometry checks on the sidebar.
Locale files gain 8 keys and lose 9 dead ones across all 13
languages.

frontend/src/utils/index.ts

@@ -685,6 +685,14 @@ export class CPUFormatter {
 }
 
 export class TimeFormatter {
+  static formatClock(unixSec: number): string {
+    const d = new Date(unixSec * 1000);
+    const hh = String(d.getHours()).padStart(2, '0');
+    const mm = String(d.getMinutes()).padStart(2, '0');
+    const ss = String(d.getSeconds()).padStart(2, '0');
+    return `${hh}:${mm}:${ss}`;
+  }
+
   static formatSecond(second: number): string {
     if (second < 60) return second.toFixed(0) + 's';
     if (second < 3600) return (second / 60).toFixed(0) + 'm';