feat(integrations): add Zapier app for Mem0

A Zapier Platform CLI app (TypeScript) wrapping the hosted Mem0 v3 REST API:
Add / Search / Get Memories / Delete actions with custom API-key auth.

- Written in TypeScript, compiles to dist/; offline unit tests (mocked z.request)
  plus live E2E; `zapier validate` clean
- Add supports custom_instructions, custom_categories, includes, excludes;
  Wait-for-Completion defaults off (extraction can exceed Zapier's 30s step limit)
- Middleware surfaces non-2xx as errors (no silent empty results)
- Anonymous opt-out telemetry (MEM0_TELEMETRY=false)
- Docs page + docs.json/llms.txt entry, ci-gate wiring, AGENTS.md rows

Split out of #6057 per review (separate PRs per integration).

docs/docs.json

@@ -348,6 +348,7 @@
                     "pages": [
                       "integrations/dify",
                       "integrations/flowise",
+                      "integrations/zapier",
                       "integrations/langchain-tools",
                       "integrations/agentops",
                       "integrations/respan",