fix(ci): perf job — point Lighthouse at /fr/ and /en/, drop spa fallback

The previous PR enabled `--localize` on the production build, so the
output structure became `dist/apps/portal-shell/browser/{en,fr}/`
with no top-level `index.html`. Two CI breakages followed:

- `nx run portal-shell:serve-static` (lhci's `startServerCommand`)
  was configured with `spa: true`. The `@nx/web:file-server` executor
  reads that as "copy `<staticFilePath>/index.html` to `404.html` for
  SPA fallback". The source file no longer exists, so the executor
  crashes with `ENOENT … copyfile … index.html` and never opens the
  port.
- Even if the server had started, `lighthouserc.js` was targeting
  `http://localhost:4200/` which produces an `http-server` directory
  listing under the new layout. Lighthouse would have run against
  that, not the SPA.

Fixes:

- Drop `spa: true` from the `serve-static` target. The executor no
  longer attempts the missing copy. Deep-link fallback in production
  is the reverse proxy's job (it routes `/{en,fr}/anything` to the
  matching `index.html`); `nx serve-static` is only used for the
  perf gate and for local prod-build inspection of the entry points.
  For deep-link testing in dev, `nx serve` is the right tool.
- Update `lighthouserc.js` `url` list to `['http://localhost:4200/fr/',
  'http://localhost:4200/en/']`, matching the directive in ADR-0019
  that both locales clear the same performance bar.

lighthouserc.js

@@ -4,20 +4,23 @@
  * Thresholds match the Google "Good" Core Web Vitals values plus the
  * Lighthouse Performance score floor we set as the project bar.
  *
- * Critical-routes list grows as features land. v1 only checks the
- * static-served portal-shell bundle (which today shows the Nx Welcome
- * placeholder); meaningful per-route assertions land alongside the
- * features that introduce those routes.
+ * Critical-routes list grows as features land. v1 checks the
+ * static-served portal-shell bundle on both locale entry points
+ * (`/fr/` is the default served at the production root via the smart
+ * redirect; `/en/` is the alternate). ADR-0019 mandates that both
+ * locales clear the same bar. Per-route assertions land alongside
+ * the features that introduce those routes.
  */
 module.exports = {
   ci: {
     collect: {
       // Serve the production bundle statically (no BFF needed for v1
-      // measurements). When real auth / routes exist, the URL list
-      // expands to the critical-routes list documented in ADR-0017.
+      // measurements). With `--localize` the build emits per-locale
+      // folders (`browser/en/`, `browser/fr/`); we serve their parent
+      // and Lighthouse hits each locale's root index.html directly.
       startServerCommand: 'pnpm nx run portal-shell:serve-static',
       startServerReadyPattern: 'Available on:',
-      url: ['http://localhost:4200/'],
+      url: ['http://localhost:4200/fr/', 'http://localhost:4200/en/'],
       numberOfRuns: 3,
       settings: {
         // Slow-4G profile so scores are stable across CI runners and