Fix #944 — snooze hint in email and Teams/Slack payloads

Lite/Services/EmailTemplateBuilder.cs

@@ -20,6 +20,7 @@ internal static class EmailTemplateBuilder
 {
     private const string EditionName = "Performance Monitor Lite";
     private const string FontStack = "-apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif";
+    private const string SnoozeHint = "To silence this alert: open Performance Monitor Lite → Settings → Manage Mute Rules";
 
     /// <summary>
     /// Builds both HTML and plain-text bodies for an alert email.
@@ -174,6 +175,10 @@ private static string BuildHtmlBody(
             sb.Append($" &middot; {emailCooldownMinutes}-minute cooldown between repeat alerts");
         }
         sb.Append("</span>");
+        if (!isTest)
+        {
+            sb.Append($"<br><span style=\"font-family:{FontStack};font-size:11px;color:#B0B0B0;\">{WebUtility.HtmlEncode(SnoozeHint)}</span>");
+        }
         sb.Append("</td></tr>");
 
         /* Close inner table */
@@ -282,6 +287,8 @@ private static string BuildPlainTextBody(
             sb.Append($"\r\nAttached: {context.AttachmentFileName}\r\n");
         }
 
+        sb.Append($"\r\n{SnoozeHint}\r\n");
+
         return sb.ToString();
     }
 }

Lite/Services/WebhookAlertService.cs

@@ -24,6 +24,7 @@ namespace PerformanceMonitorLite.Services;
 public class WebhookAlertService
 {
     private const string EditionName = "Performance Monitor Lite";
+    private const string SnoozeHint = "To silence this alert: open Performance Monitor Lite → Settings → Manage Mute Rules";
     private static readonly JsonSerializerOptions s_jsonOptions = new() { PropertyNamingPolicy = null };
 
     private readonly ConcurrentDictionary<string, DateTime> _cooldowns = new();
@@ -221,6 +222,11 @@ internal static string BuildTeamsPayload(
             }
         };
 
+        if (!isTest)
+        {
+            sections.Add(new { text = SnoozeHint });
+        }
+
         var card = new
         {
             @type = "MessageCard",
@@ -346,13 +352,19 @@ internal static string BuildSlackPayload(
             }
         }
 
+        var contextElements = new List<object>
+        {
+            new { type = "mrkdwn", text = $"Sent by {EditionName}" }
+        };
+        if (!isTest)
+        {
+            contextElements.Add(new { type = "mrkdwn", text = SnoozeHint });
+        }
+
         blocks.Add(new
         {
             type = "context",
-            elements = new object[]
-            {
-                new { type = "mrkdwn", text = $"Sent by {EditionName}" }
-            }
+            elements = contextElements
         });
 
         var payload = new