fix(types): resolve context-relay payload resolution and typing issues

- Fix `handoffProviders` and `nextBody` unknown property TS errors in contextHandoff
- Correct fallback payload parsing from responses `input` array in combo service

tests/integration/_chatPipelineHarness.mjs

@@ -203,6 +203,8 @@ export async function createChatPipelineHarness(prefix) {
   async function resetStorage() {
     globalThis.fetch = originalFetch;
     clearInflight();
+    idempotencyLayerModule.clearIdempotency();
+    semanticCacheModule.clearCache();
     resetAllAvailability();
     resetAllCircuitBreakers();
     apiKeysDb.resetApiKeyState();
@@ -220,6 +222,8 @@ export async function createChatPipelineHarness(prefix) {
     BaseExecutor.RETRY_CONFIG.delayMs = originalRetryDelayMs;
     globalThis.fetch = originalFetch;
     clearInflight();
+    idempotencyLayerModule.clearIdempotency();
+    semanticCacheModule.clearCache();
     clearSkillState();
     resetAllAvailability();
     resetAllCircuitBreakers();