fix: restrict dynamic journey responses

frontend/src/lib/birth-time-journey-response-schema.ts

@@ -108,9 +108,13 @@ function dynamicActionMatchesPhase(value: {
 
 const dynamicJourneyResponseSchema = z.object({
   ...responseCore,
-  scoring: versionedScoringSchema.nullable(),
-  answers: z.record(answerSchema).readonly(),
-  lifeEvents: z.array(lifeEventSchema).readonly(),
+  questionnaire: z.null(),
+  scoring: z.null(),
+  answers: z.record(answerSchema).refine(
+    (answers) => Object.keys(answers).length === 0,
+    "dynamic answers are server-private",
+  ).readonly(),
+  lifeEvents: z.array(lifeEventSchema).max(0, "dynamic life events are server-private").readonly(),
   candidateResult: candidateResultSchema.nullable(),
   journeyProtocol: z.literal("dynamic-choice-v2"),
   turnVersion: z.number().int().nonnegative(),

frontend/src/lib/birth-time-journey-response.ts

@@ -140,10 +140,10 @@ export function storedDynamicJourneyResponse(
   return {
     caseId: stored.id,
     snapshot: stored.snapshot,
-    questionnaire: stored.questionnaire,
-    scoring: stored.scoring ?? null,
-    answers: stored.answers,
-    lifeEvents: stored.lifeEvents ?? [],
+    questionnaire: null,
+    scoring: null,
+    answers: {},
+    lifeEvents: [],
     candidateResult: stored.candidateResult ?? null,
     evidenceDraft: null,
     ...stored.dynamicTurnState,