feat(platform): route scheduler notifications through platform messenger

tests/GmRelay.Bot.Tests/Platform/PlatformContractsTests.cs

@@ -51,4 +51,42 @@ public sealed class PlatformContractsTests
         Assert.Equal(PlatformKind.Discord, message.Group.Platform);
         Assert.Same(view, message.View);
     }
+
+    [Fact]
+    public void PlatformNotificationContracts_ShouldBeSdkAssemblyFree()
+    {
+        var contractTypes = new[]
+        {
+            typeof(PlatformSessionParticipant),
+            typeof(PlatformConfirmationRequest),
+            typeof(PlatformJoinLinkNotification),
+            typeof(PlatformDirectSessionNotification),
+            typeof(PlatformRsvpMessageUpdate),
+            typeof(PlatformRsvpOutcomeNotification),
+            typeof(PlatformRescheduleVoteUpdate)
+        };
+
+        Assert.All(contractTypes, type =>
+        {
+            var refs = string.Join(" ", type.Assembly.GetReferencedAssemblies().Select(value => value.Name));
+            Assert.DoesNotContain("Telegram", refs, StringComparison.OrdinalIgnoreCase);
+            Assert.DoesNotContain("NetCord", refs, StringComparison.OrdinalIgnoreCase);
+        });
+    }
+
+    [Fact]
+    public void PlatformMessenger_ShouldExposeSchedulerNotificationOperations()
+    {
+        var methods = typeof(IPlatformMessenger)
+            .GetMethods()
+            .Select(method => method.Name)
+            .ToHashSet(StringComparer.Ordinal);
+
+        Assert.Contains("SendConfirmationRequestAsync", methods);
+        Assert.Contains("UpdateConfirmationRequestAsync", methods);
+        Assert.Contains("SendJoinLinkNotificationAsync", methods);
+        Assert.Contains("SendDirectSessionNotificationAsync", methods);
+        Assert.Contains("SendRsvpOutcomeAsync", methods);
+        Assert.Contains("UpdateRescheduleVoteAsync", methods);
+    }
 }