refactor(channels): unify target parsing

src/channels/plugins/normalize/whatsapp.ts

@@ -0,0 +1,15 @@
+import { normalizeWhatsAppTarget } from "../../../whatsapp/normalize.js";
+
+export function normalizeWhatsAppMessagingTarget(raw: string): string | undefined {
+  const trimmed = raw.trim();
+  if (!trimmed) return undefined;
+  return normalizeWhatsAppTarget(trimmed) ?? undefined;
+}
+
+export function looksLikeWhatsAppTargetId(raw: string): boolean {
+  const trimmed = raw.trim();
+  if (!trimmed) return false;
+  if (/^whatsapp:/i.test(trimmed)) return true;
+  if (trimmed.includes("@")) return true;
+  return /^\+?\d{3,}$/.test(trimmed);
+}