refactor(native-chat): give the answered-turn schema its own module

Keeps the journal schema file within its line limit.

src/shared/agent-session-answered-turn-schema.ts

@@ -0,0 +1,7 @@
+import { z } from 'zod'
+
+/** A submission's answered turn as published. `via` is a string, as `dispatchState` is: a newer
+ *  host may name another way of joining. null: the host recorded no turn. */
+export const AgentJournalAnsweredTurnSchema = z
+  .object({ turnItemId: z.string().min(1), via: z.string().min(1) })
+  .nullable()

src/shared/agent-session-journal-schemas.ts

@@ -16,6 +16,7 @@
 import { z } from 'zod'
 import { AgentSessionContextUsageSchema } from './agent-session-context-usage-schema'
 import { AgentSessionFailureFactSchema } from './agent-session-failure-fact-schema'
+import { AgentJournalAnsweredTurnSchema } from './agent-session-answered-turn-schema'
 import type {
   AgentJournalItemBody,
   AgentJournalMessageItem,
@@ -319,11 +320,7 @@ export const AgentJournalSubmissionSchema = z.object({
   submittedAt: z.number(),
   resolvedAt: z.number().nullable(),
   submittedSequence: z.number().int().optional(),
-  // `via` is a string, as `dispatchState` is: a newer host may name another way of joining.
-  answeredInTurn: z
-    .object({ turnItemId: z.string().min(1), via: z.string().min(1) })
-    .nullable()
-    .optional(),
+  answeredInTurn: AgentJournalAnsweredTurnSchema.optional(),
   recovered: z.literal(true).optional(),
   handoverRecorded: z.literal(true).optional(),
   handedOverAt: z.number().optional(),