fix(security): SSRF guard on the executor dispatch path (provider baseUrl)

A persisted, caller-supplied providerSpecificData.baseUrl reached fetch() on the
runtime dispatch path with no SSRF guard, so a manage-scope actor (or an
anonymous one on a keyless install) could point a provider at loopback /
internal / cloud-metadata hosts and reach the instance metadata service.
BaseExecutor now mirrors the provider validation guard before every upstream
fetch (fetchWithStartTimeout covers retries/fallback URLs; countTokens too), with
the same call added to the glm and nlpcloud executors' own fetch paths. Local /
self-hosted providers stay exempt; default block-metadata mode stops the
cloud-metadata IMDS pivot, public-only mode also blocks private targets.

Reported by @rafaelfiguereod-stack via GHSA-4f49-hj64-448x.

tests/unit/base-executor-ssrf-guard.test.ts

@@ -0,0 +1,38 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { DefaultExecutor } from "../../open-sse/executors/default.ts";
+
+// GHSA-4f49-hj64-448x — a persisted, caller-supplied providerSpecificData.baseUrl
+// reaches fetch() on the runtime dispatch path with no SSRF guard. BaseExecutor
+// now mirrors the provider VALIDATION guard before every upstream fetch. In the
+// shipped default (block-metadata) mode the cloud-metadata IMDS pivot is blocked
+// for non-local providers, public upstreams pass, and local / self-hosted
+// providers (vLLM, LM Studio, Ollama, …) stay exempt so loopback/LAN keeps working.
+
+function guardOf(provider: string) {
+  const exec = new DefaultExecutor(provider) as unknown as {
+    assertOutboundUrlAllowed(url: string): void;
+  };
+  return (url: string) => exec.assertOutboundUrlAllowed(url);
+}
+
+test("BaseExecutor blocks cloud-metadata for a non-local provider (GHSA-4f49-hj64-448x)", () => {
+  const guard = guardOf("openai");
+  assert.throws(() => guard("http://169.254.169.254/latest/meta-data/iam/security-credentials/"));
+  // IPv4-mapped IPv6 spelling of the same address (folded out by #10843).
+  assert.throws(() => guard("http://[::ffff:169.254.169.254]/latest/meta-data/"));
+});
+
+test("BaseExecutor allows a public upstream URL for a non-local provider", () => {
+  const guard = guardOf("openai");
+  assert.doesNotThrow(() => guard("https://api.openai.com/v1/chat/completions"));
+});
+
+test("BaseExecutor exempts local / self-hosted providers from the outbound guard", () => {
+  assert.doesNotThrow(() => guardOf("ollama-local")("http://127.0.0.1:11434/v1/chat/completions"));
+  assert.doesNotThrow(() => guardOf("lm-studio")("http://192.168.1.50:1234/v1/chat/completions"));
+});
+
+test("BaseExecutor guard is a no-op for an empty URL", () => {
+  assert.doesNotThrow(() => guardOf("openai")(""));
+});