fix(app): settle out-of-band submissions compatibly

packages/protocol/src/messages.ts

@@ -3708,6 +3708,8 @@ export const SendAgentMessageResponseMessageSchema = z.object({
     agentId: z.string(),
     accepted: z.boolean(),
     error: z.string().nullable(),
+    // COMPAT(messageSubmissionDisposition): added in v0.2.3, remove optional parsing after 2027-01-27.
+    outOfBand: z.boolean().optional(),
   }),
 });