Hotfix: trailingSlash:true so GitHub Pages serves the locale roots

The previous deploy went live but every visitor hit a 404. Root cause:

GitHub Pages serves the URL `/foo/` by looking for `out/foo/index.html`.
Next.js's static export with the default `trailingSlash: false` instead
emits `out/foo.html`, which Pages only serves for `/foo` (no trailing
slash).

The i18n root redirect in app/page.tsx points users at
`/<defaultLocale>/` (with slash) because that is what next-intl's
`<Link>` components generate. So every visitor landed on
`https://proxmenux.com/en/` → Pages looked for `out/en/index.html`,
did not find it (the export had emitted `out/en.html`), and fell back
to `out/404.html`. Result: the site looked deployed but every page
was a Next.js 404 template.

Setting `trailingSlash: true` makes the export emit
`out/<route>/index.html` for every page — locale roots
(`out/en/index.html`, `out/es/index.html`), nested doc pages
(`out/en/docs/monitor/dashboard/settings/index.html`, etc.), changelog,
guides — so Pages serves them directly.

Local verification: 232 pages built, root redirect intact at
out/index.html, and every locale + doc + guide URL now resolves to
its own index.html.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/next.config.mjs

@@ -13,6 +13,18 @@ const withNextIntl = createNextIntlPlugin('./i18n/request.ts')
 /** @type {import('next').NextConfig} */
 const nextConfig = {
   output: "export",
+  // GitHub Pages serves a directory URL `/foo/` by looking for
+  // `out/foo/index.html`. Next.js's default static export with
+  // `trailingSlash: false` emits `out/foo.html` instead, which Pages
+  // only serves for the bare URL `/foo` (no trailing slash). The
+  // i18n root redirect points users at `/<defaultLocale>/` (with
+  // slash) — so every visitor would land on a 404. Enabling
+  // trailingSlash makes Next.js emit `out/<route>/index.html` for
+  // every page, including `out/en/index.html` and `out/es/index.html`
+  // so the locale roots load correctly. Internal `<Link>` URLs from
+  // next-intl already include the trailing slash, so this aligns
+  // export, runtime navigation and Pages serving.
+  trailingSlash: true,
   eslint: {
     ignoreDuringBuilds: true,
   },