refactor: add inbound context helpers

src/channels/chat-type.ts

@@ -0,0 +1,11 @@
+export type NormalizedChatType = "direct" | "group" | "channel";
+
+export function normalizeChatType(raw?: string): NormalizedChatType | undefined {
+  const value = raw?.trim().toLowerCase();
+  if (!value) return undefined;
+  if (value === "direct" || value === "dm") return "direct";
+  if (value === "group") return "group";
+  if (value === "channel" || value === "room") return "channel";
+  return undefined;
+}
+