perf(test): run dashboard src tests in node env, app tests in jsdom

The dashboard backend (Express routes, services) lives under src/ and is pure
Node logic, but every test was paying for jsdom env init plus full CSS-import
processing. Split via environmentMatchGlobs so app/** keeps jsdom (React UI)
and src/** runs in node by default. Two src tests opt back into jsdom:

- status-bar.test.ts uses window.matchMedia.
- proxy-routes.test.ts asserts on DOMException constructor.name, which jsdom
  reports as "AbortError" but node reports as "DOMException".

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/dashboard/src/__tests__/proxy-routes.test.ts

@@ -1,3 +1,8 @@
+// @vitest-environment jsdom
+// Uses DOMException("Aborted", "AbortError") whose constructor.name behaves
+// differently in node (resolves to "DOMException") vs jsdom ("AbortError"),
+// which the proxy error classifier asserts on.
+
 import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
 import { EventEmitter } from "node:events";
 import { request, get } from "../test-request.js";

packages/dashboard/src/__tests__/status-bar.test.ts

@@ -1,3 +1,5 @@
+// @vitest-environment jsdom
+
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { StatusBarManager } from "../plugins/status-bar.js";
 

packages/dashboard/vitest.config.ts

@@ -16,7 +16,14 @@ export default defineConfig({
     },
   },
   test: {
-    environment: "jsdom",
+    // `app/**` is React UI — needs jsdom + CSS. `src/**` is the Express
+    // backend, mostly Node-only logic; running it in node env trims jsdom
+    // env+CSS-include cost. The handful of src tests that genuinely need DOM
+    // opt-in via `// @vitest-environment jsdom`.
+    environment: "node",
+    environmentMatchGlobs: [
+      ["app/**", "jsdom"],
+    ],
     // Process CSS imports so jsdom-based tests that assert on getComputedStyle
     // see the actual rules from co-located component CSS files.
     css: { include: [/.+/] },