fix(integrations): address code-review findings

n8n: throw on FAILED memory events (was silently returned), poll on any
non-terminal status (PENDING or RUNNING), use top_k (not limit) for
search, coerce search/getAll responses to arrays, guard invalid-JSON
metadata, reject empty updates, mark user_id required; lint clean.

Zapier: coerce boolean fields (String(x) !== 'false') + boolean defaults
so "Wait"/"Infer = No" are honored, throw on HTTP >= 400 (was silent
empty/fake-success), throw on FAILED events, use top_k, numeric coercion
with clamping, mark user_id required.

integrations/zapier-mem0/middleware.js

@@ -14,7 +14,9 @@ const includeApiKey = (request, z, bundle) => {
 	return request;
 };
 
-// Surface auth failures as Zapier auth errors so users are prompted to reconnect.
+// Surface HTTP failures as errors. z.request does NOT throw on non-2xx by
+// default, so without this a 4xx/5xx would flow downstream as a fake success
+// (empty search results / error body returned as a created memory).
 const handleBadResponses = (response, z, _bundle) => {
 	if (response.status === 401 || response.status === 403) {
 		throw new z.errors.Error(
@@ -23,6 +25,15 @@ const handleBadResponses = (response, z, _bundle) => {
 			response.status,
 		);
 	}
+	if (response.status >= 400) {
+		const data = response.data || {};
+		const detail = data.detail || data.error || data.message || response.content || 'unknown error';
+		throw new z.errors.Error(
+			`Mem0 API request failed (HTTP ${response.status}): ${detail}`,
+			'Mem0ApiError',
+			response.status,
+		);
+	}
 	return response;
 };