fix(integrations): address review feedback on Zapier and n8n

Zapier:
- Bound the poll budget under Zapier's step timeout and default Wait for
  Completion off; timeout message notes the add likely still succeeded
- Add offline unit tests (mocked z.request) and run them in CI
- Expose a Page input on Get Memories
- Encode memory_id in the delete path
- Update E2E to test the default no-wait path (add then search-retry)

n8n:
- Clarify the Infer description (controls extraction, not waiting)
- Add an App ID field and require at least one entity id before add
- Pass itemIndex into pollEvent errors
- Unwrap event results so wait-path output matches search and get many

integrations/zapier-mem0/creates/delete_memory.js

@@ -1,9 +1,9 @@
 'use strict';
 
 const perform = async (z, bundle) => {
-	// Trailing slash required (Django APPEND_SLASH).
+	// Trailing slash required (Django APPEND_SLASH); id encoded so a stray slash can't mistarget the path.
 	const response = await z.request({
-		url: `/v1/memories/${bundle.inputData.memory_id}/`,
+		url: `/v1/memories/${encodeURIComponent(bundle.inputData.memory_id)}/`,
 		method: 'DELETE',
 	});
 	return response.data || { message: 'Deleted', memory_id: bundle.inputData.memory_id };