fix(qa): use full tool profile for node MCP live proof (#125683)

* fix(gateway): share node tool snapshots across chunks

* docs(gateway): explain node snapshot ownership

* fix(qa): expose node MCP tool in live proof

test/e2e/qa-lab/runtime/gateway-node-mcp.live.test.ts

@@ -195,7 +195,11 @@ describe.skipIf(!LIVE_ENABLED)("OpenAI cross-placement MCP model proof", () => {
                 defaults: { ...cfg.agents?.defaults, ...live.agents?.defaults },
                 entries: {
                   ...cfg.agents?.entries,
-                  qa: { ...cfg.agents?.entries?.qa, model: { primary: MODEL_REF } },
+                  qa: {
+                    ...cfg.agents?.entries?.qa,
+                    model: { primary: MODEL_REF },
+                    tools: { ...cfg.agents?.entries?.qa?.tools, profile: "full" },
+                  },
                 },
               },
               mcp: { servers: gatewayServers },