test(web): run the dashboard test project in development mode

React 19 only ships `act` in its development build. The jsdom suites in
`web/` drive components through `act()`, so when vitest inherits an
ambient `NODE_ENV=production` — the shell that launched the app, a
packaged CI step, an editor terminal — `React.act` resolves to undefined
and every `createRoot` test in the project fails with
`TypeError: act is not a function`.

Pin the test worker to `NODE_ENV=development` via the project's
`test.env` so the suite no longer depends on the ambient environment.
App runtime and production builds are unaffected; this only applies to
the vitest worker.

Same class of failure as #77409 (and the same fix shape as #77421), one
workspace over: that issue and PR cover `apps/desktop/vitest.config.ts`,
while `web/vitest.config.ts` has no equivalent guard.

Before (clean main, NODE_ENV=production):
  Test Files  3 failed | 33 passed (36)
  Tests      43 failed | 232 passed (275)

After:
  Test Files  36 passed (36)
  Tests      275 passed (275)

web/vitest.config.ts

@@ -26,5 +26,16 @@ export default defineConfig({
     // timeout (main run 34600757569: 5079ms). Same headroom rationale as
     // apps/desktop/vitest.config.ts; genuinely hung tests still fail.
     testTimeout: 15_000,
+    // React 19 ships `act` only in its development build, and the jsdom suites
+    // here drive components through `act()`. A shell that already exports
+    // NODE_ENV=production (the one that launched the app, a packaged CI step,
+    // an editor terminal) is inherited by vitest, `React.act` resolves to
+    // undefined, and every `createRoot` test in this project fails with
+    // "act is not a function". Pin the worker to development so the suite is
+    // independent of the ambient environment; app runtime and production
+    // builds are untouched.
+    env: {
+      NODE_ENV: "development",
+    },
   },
 });