feat(workspace): add cpu core status display and safer quick command actions

Expose `cpuCores` in backend status collection with multi-command fallback
and surface it in the status panel as a localized CPU core badge under the
CPU model.

Adjust terminal group UX by adding a server-level close-all control in the
SSH tab group header.

Reduce accidental quick command execution by switching list interaction to
single-click select + double-click execute, while preserving keyboard Enter
and context-menu execution paths.

packages/frontend/src/locales/ja-JP.json

@@ -1365,6 +1365,7 @@
         "bytesPerSecond": "B/秒",
         "cpuLabel": "CPU:",
         "cpuModelLabel": "CPU モデル:",
+        "cpuCoresValue": "{count} コア",
         "diskLabel": "ディスク:",
         "errorPrefix": "エラー:",
         "gigaBytes": "GB",
@@ -1587,6 +1588,7 @@
           "selectServerTitle": "接続するサーバーを選択",
           "showTransferProgressTooltip": "転送進捗の表示/非表示",
           "newTerminalTooltip": "現在のサーバーに新しいターミナルを追加",
+          "closeConnectionGroupTooltip": "{name} の端末をすべて閉じる ({count} 件)",
           "openConnectionPickerTooltip": "別のサーバーを選択",
           "terminalBadge": "端末 {index}"
       },