feat(ops): health-fail alerts, optional DB backup, admin UX polish

Wire jobs-worker health probes to Discord/email alerts with cooldown, optional mysqldump, rate-limit /api/health, mark-all-read alerts, ConfirmDialog on destructive admin actions, and raise coverage floors.

Co-authored-by: Cursor <[email protected]>

src/messages/en.json

@@ -2416,15 +2416,22 @@
 			},
 			"alerts": {
 				"title": "Alerts",
-				"subtitle": "Send hotel-wide alerts and view recent alerts",
+				"subtitle": "Send hotel-wide alerts and view recent ops alerts",
 				"sendAlert": "Send hotel alert",
-				"recentAlerts": "Recent alerts",
+				"recentAlerts": "Recent alerts ({count})",
+				"noAlerts": "No recent alerts",
 				"noRecentAlerts": "No recent alerts",
+				"alertsShown": "Shown",
+				"critical": "Critical",
+				"warnings": "Warnings",
+				"unread": "Unread",
+				"markAllRead": "Mark all read",
 				"form": {
 					"title": "Alert title",
 					"titlePlaceholder": "e.g. Server maintenance in 10 minutes",
 					"message": "Alert message",
 					"messagePlaceholder": "Write the alert message…",
+					"description": "Broadcasts via RCON <code>hotelalert</code> to online users.",
 					"type": "Type",
 					"typeHotel": "Hotel-wide alert",
 					"typeStaff": "Staff only",
@@ -2437,6 +2444,9 @@
 				"colSentBy": "Sent by",
 				"colType": "Type",
 				"colDate": "Date",
+				"colWhen": "When",
+				"colSeverity": "Severity",
+				"colMessage": "Message",
 				"colActions": "Actions"
 			},
 			"logs": {