chore(integrations): use pnpm, real Mem0 icon, fix Zapier field defaults

- Switch both packages from npm to pnpm (pnpm-lock.yaml) to match the
  repo convention (openclaw / pi-agent-plugin / vercel-ai-sdk); gitignore
  package-lock.json.
- Replace the placeholder n8n node icon with the real Mem0 mark (same
  asset used by integrations/mem0-plugin).
- Zapier: revert boolean/integer field defaults to strings — Zapier's
  schema requires string defaults (zapier validate now passes with 0
  errors). Runtime coercion (String(x)!=='false', Number()) is unchanged.

integrations/zapier-mem0/creates/add_memory.js

@@ -98,14 +98,14 @@ module.exports = {
 				key: 'infer',
 				label: 'Infer',
 				type: 'boolean',
-				default: true,
+				default: 'true',
 				helpText: 'Run LLM extraction (async). Turn off to store verbatim (synchronous).',
 			},
 			{
 				key: 'waitForCompletion',
 				label: 'Wait for Completion',
 				type: 'boolean',
-				default: true,
+				default: 'true',
 				helpText: 'Poll until extraction finishes and return the resulting memories.',
 			},
 		],