fix(n8n): escape ids in URLs, add agent/run filters, run tests in CI

Three review findings on the Mem0 n8n node:

- Memory IDs and event IDs were interpolated raw into request paths, so a
  value containing / or .. could reach a different endpoint than intended.
  Wrap all four sites in encodeURIComponent.

- Search and Get Many could only filter by user_id, leaving agent- and
  run-scoped memories unreachable from the node. Both now accept User ID,
  Agent ID, and Run ID. Multiple ids combine with OR because Mem0 indexes
  entities separately and an AND across them matches nothing. User ID is
  no longer marked required; the node still fails with a clear message
  when all three are empty, rather than letting the API return a raw 400.

- n8n-nodes-mem0-checks.yml ran lint and build but never the jest suite,
  so the tests could rot unnoticed. Add a test job matching the layout of
  pi-agent-plugin-checks.yml.

Tests cover flat single-entity filters, the OR combination, agent-only
listing, the empty-entity guard on both operations, and id escaping in
the get/delete/poll URLs. Docs and README document the new fields and the
OR semantics.

integrations/n8n-nodes-mem0/README.md

@@ -20,7 +20,7 @@ The **Memory** resource supports:
 | --- | --- | --- |
 | **Add** | Extract and store memories from messages | `POST /v3/memories/add/` |
 | **Search** | Semantic search over stored memories | `POST /v3/memories/search/` |
-| **Get Many** | List memories for a user (single page, or **Return All**) | `POST /v3/memories/` |
+| **Get Many** | List stored memories (single page, or **Return All**) | `POST /v3/memories/` |
 | **Get** | Retrieve a single memory by ID | `GET /v1/memories/{id}/` |
 | **Update** | Update a memory's text or metadata | `PUT /v1/memories/{id}/` |
 | **Delete** | Delete a single memory by ID | `DELETE /v1/memories/{id}/` |
@@ -36,6 +36,12 @@ Two independent controls:
 
 **Custom Instructions** and **Custom Categories** (also under Additional Fields) steer what extraction keeps for that call.
 
+### Entity filters on Search & Get Many
+
+Both take **User ID**, **Agent ID**, and **Run ID**, and at least one is required — the API rejects a query with no entity scope, and the node fails with a clear message before calling it.
+
+Supplying several combines them with **OR**, giving the union of those scopes. Mem0 indexes each entity separately, so an `AND` across `user_id` and `agent_id` matches nothing even for a memory written with both. To narrow instead of widen, run one operation per entity id.
+
 ## Credentials
 
 You need a Mem0 API key. Create one at [app.mem0.ai](https://app.mem0.ai) → Settings → API Keys. The key is sent as `Authorization: Token <key>`.
@@ -46,7 +52,7 @@ This node is also **usable as a tool** by n8n's AI Agent node — attach it so a
 
 A typical loop:
 
-1. **Search** memory before answering, filtered by `User ID`.
+1. **Search** memory before answering, filtered by `User ID` (or `Agent ID` / `Run ID`).
 2. **Add** durable facts after a meaningful exchange.
 
 Memory writes are asynchronous by default; allow a moment after an Add before searching for the same content.