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.

internal/web/translation/ja-JP.json

@@ -106,7 +106,6 @@
     "routing": "ルーティング",
     "outbounds": "アウトバウンド",
     "apiDocs": "API ドキュメント",
-    "link": "リンク管理",
     "donate": "寄付",
     "hosts": "ホスト",
     "docs": "ドキュメント",
@@ -127,12 +126,9 @@
     },
     "index": {
       "cpu": "CPU",
-      "logicalProcessors": "論理プロセッサ",
-      "frequency": "周波数",
       "swap": "スワップ",
       "storage": "ストレージ",
       "memory": "メモリ",
-      "threads": "スレッド",
       "xrayStatus": "Xray",
       "stopXray": "停止",
       "restartXray": "再起動",
@@ -153,7 +149,6 @@
       "xrayStatusRunning": "実行中",
       "xrayStatusStop": "停止",
       "xrayStatusError": "エラー",
-      "operationHours": "システム稼働時間",
       "systemHistoryTitle": "システム履歴",
       "historyTitleCpu": "CPU 使用率",
       "historyTitleMem": "メモリ使用率",
@@ -171,7 +166,6 @@
       "historyTabLoad": "負荷",
       "historyTabConnections": "接続数",
       "historyTabDiskUsage": "ディスク使用量",
-      "charts": "チャート",
       "xrayMetricsTitle": "Xray メトリクス",
       "xrayTitleHeap": "割り当て済みヒープメモリ",
       "xrayTitleSys": "OS から確保したメモリ",
@@ -200,7 +194,6 @@
       "overallSpeed": "全体の速度",
       "upload": "アップロード",
       "download": "ダウンロード",
-      "totalData": "総データ量",
       "sent": "送信",
       "received": "受信",
       "xraySwitchVersionDialog": "Xrayのバージョンを本当に変更しますか？",
@@ -250,7 +243,18 @@
       "exportDatabasePgDesc": "現在のデータベースの PostgreSQL ダンプ (.dump) を端末にダウンロードするにはクリックしてください。",
       "importDatabasePgDesc": "データベースを復元するために PostgreSQL バックアップ (.dump)、SQLite データベース (.db)、または SQLite 移行ダンプを選択してアップロードするにはクリックしてください。現在のすべてのデータが置き換えられます。",
       "migrationDownload": "移行ファイルをダウンロード",
-      "migrationDownloadPgDesc": "PostgreSQL のデータから作成した .db SQLite データベースをダウンロードします。このパネルを SQLite で実行する準備が整います。"
+      "migrationDownloadPgDesc": "PostgreSQL のデータから作成した .db SQLite データベースをダウンロードします。このパネルを SQLite で実行する準備が整います。",
+      "avg": "平均",
+      "peak": "ピーク",
+      "free": "空き",
+      "openSockets": "オープンソケット",
+      "throughputSub": "インターフェース合計",
+      "avgWindow": "期間平均",
+      "healthWarm": "{list} — 高めです",
+      "healthCritical": "{list} — 危険水準",
+      "panel": "パネル",
+      "threads": "スレッド",
+      "uptime": "稼働時間"
     },
     "inbounds": {
       "totalDownUp": "総アップロード / ダウンロード",