chore(integrations): address review — Zapier LICENSE, docs, tidy job names

- Add MIT LICENSE to zapier-mem0 (package.json declared MIT but shipped no
  file; every peer commits one) + keywords/author/homepage for parity.
- Document the n8n and Zapier checks workflows in the AGENTS.md CI table.
- Title-case the ci-gate job display names (n8n Node, Zapier App) to match
  the other integration jobs.

.github/workflows/ci-gate.yml

@@ -147,14 +147,14 @@ jobs:
     secrets: inherit
 
   n8n-nodes-mem0:
-    name: n8n node
+    name: n8n Node
     needs: changes
     if: needs.changes.outputs.n8n_nodes_mem0 == 'true'
     uses: ./.github/workflows/n8n-nodes-mem0-checks.yml
     secrets: inherit
 
   zapier-mem0:
-    name: Zapier app
+    name: Zapier App
     needs: changes
     if: needs.changes.outputs.zapier_mem0 == 'true'
     uses: ./.github/workflows/zapier-mem0-checks.yml