refactor: reorganize Application layer into folder structure

src/GreenHome.Application/Dtos/Common/AlertCheckResult.cs

@@ -0,0 +1,16 @@
+namespace GreenHome.Application;
+
+/// <summary>
+/// Result of alert checking, used by TelemetryController.Create to build the line-protocol response
+/// </summary>
+public sealed class AlertCheckResult
+{
+    /// <summary>List of alert messages (condition alerts + power status)</summary>
+    public List<string> Messages { get; set; } = new();
+
+    /// <summary>Comma-separated recipient phone numbers</summary>
+    public string? Recipients { get; set; }
+
+    /// <summary>Power status: "connected", "disconnected", or null if unchanged</summary>
+    public string? PowerStatus { get; set; }
+}