Feature/default messenger delivery target (openclaw#16985) thanks @KirillShchetinin

Verified:
- pnpm build
- pnpm check
- pnpm test:macmini

Co-authored-by: KirillShchetinin <13061871+KirillShchetinin@users.noreply.github.com>
Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

src/channels/plugins/types.adapters.ts

@@ -63,6 +63,10 @@ export type ChannelConfigAdapter<ResolvedAccount> = {
     accountId?: string | null;
     allowFrom: Array<string | number>;
   }) => string[];
+  resolveDefaultTo?: (params: {
+    cfg: OpenClawConfig;
+    accountId?: string | null;
+  }) => string | undefined;
 };
 
 export type ChannelGroupAdapter = {