fix(routing): only route to originating channel when cross-provider

When OriginatingChannel matches Surface (same provider), use normal
dispatcher. Only route via routeReply() when they differ, ensuring
cross-provider messages (e.g., Telegram queued while Slack active)
get routed back to their origin.

src/imessage/monitor.ts

@@ -366,6 +366,7 @@ export async function monitorIMessageProvider(
       SenderName: sender,
       SenderId: sender,
       Provider: "imessage",
+      Surface: "imessage",
       MessageSid: message.id ? String(message.id) : undefined,
       Timestamp: createdAt,
       MediaPath: mediaPath,