complete i18n migration to /[locale]/ with EN+ES content

Full rewrite of the docs site under app/[locale]/ with next-intl
in localePrefix:"always" mode. Every page now exists at both
/en/<path> and /es/<path>; the root / shows a meta-refresh + JS
redirect to /<defaultLocale>/ so GitHub Pages serves something
on the apex URL.

Highlights:
- 107 doc pages migrated to file-per-page JSON namespaces under
  messages/en/ and messages/es/. Spanish content is fully
  translated (no copy-of-English placeholders).
- New documentation for the Active Suppressions section in the
  Settings tab and the per-event Dismiss dropdown in the Health
  Monitor modal.
- New screenshots: dismiss-duration-dropdown.png and an updated
  health-suppression-settings.png.
- Pagefind integrated for client-side search; index is built on
  every CI deploy (not committed).
- RSS feeds: per-locale at /<locale>/rss.xml plus root /rss.xml
  for backward compat.
- Removed the dead app/[locale]/guides/[slug]/ route — every
  guide now has its own static page and no markdown source
  remains.
- Fixed orphan link /guides/nvidia -> /guides/nvidia-manual in
  docs/hardware/nvidia-host.
- Removed obsolete components (footer2, calendar, drawer).

Verified locally with `npm ci && npm run build`: 2804 files in
out/, 231 pages indexed by pagefind, root redirect intact, both
locale roots and the new Active Suppressions docs render OK.

web/i18n/routing.ts

@@ -0,0 +1,27 @@
+import { defineRouting } from "next-intl/routing"
+
+/**
+ * i18n routing configuration for the ProxMenux web docs.
+ *
+ * - English is the default locale: the docs grew up in English and the
+ *   homelab/Proxmox audience is primarily international. New locales
+ *   land progressively; missing translations should fall back to the
+ *   English message rather than 404.
+ *
+ * - `localePrefix: "always"` is required for `output: "export"` static
+ *   builds and gives cleaner SEO: every URL carries an explicit locale
+ *   segment (`/en/docs/...`, `/es/docs/...`) so hreflang and Google's
+ *   per-language indexing work without ambiguity.
+ *
+ * - When adding a new locale here, also create
+ *   `messages/<locale>/common.json` (mandatory) and start
+ *   page-specific files under `messages/<locale>/docs/...`. See
+ *   `CONTRIBUTING-TRANSLATIONS.md`.
+ */
+export const routing = defineRouting({
+  locales: ["en", "es"],
+  defaultLocale: "en",
+  localePrefix: "always",
+})
+
+export type Locale = (typeof routing.locales)[number]