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/components/language-switcher.tsx

@@ -0,0 +1,53 @@
+"use client"
+
+import { useLocale, useTranslations } from "next-intl"
+import { useRouter, usePathname } from "@/i18n/navigation"
+import { Languages } from "lucide-react"
+import {
+  DropdownMenu,
+  DropdownMenuContent,
+  DropdownMenuItem,
+  DropdownMenuTrigger,
+} from "./ui/dropdown-menu"
+import { routing } from "@/i18n/routing"
+
+/**
+ * Language switcher dropdown for the navbar.
+ *
+ * Reads the active locale from next-intl and replaces it in the URL on
+ * selection. The locale-aware `usePathname` and `useRouter` from
+ * @/i18n/navigation strip the current `[locale]` prefix when reading
+ * and re-add the chosen one when navigating, so the user stays on the
+ * same logical page after switching language.
+ */
+export function LanguageSwitcher() {
+  const t = useTranslations("language")
+  const locale = useLocale()
+  const router = useRouter()
+  const pathname = usePathname()
+
+  const labels: Record<string, string> = {
+    en: t("en"),
+    es: t("es"),
+  }
+
+  return (
+    <DropdownMenu>
+      <DropdownMenuTrigger className="flex items-center gap-1.5 px-2 py-1 rounded-md hover:bg-secondary transition-colors text-sm font-medium" aria-label={t("switcher")}>
+        <Languages className="h-4 w-4" />
+        <span className="uppercase">{locale}</span>
+      </DropdownMenuTrigger>
+      <DropdownMenuContent align="end">
+        {routing.locales.map((loc) => (
+          <DropdownMenuItem
+            key={loc}
+            onSelect={() => router.replace(pathname, { locale: loc })}
+            className={loc === locale ? "font-semibold" : ""}
+          >
+            {labels[loc] || loc}
+          </DropdownMenuItem>
+        ))}
+      </DropdownMenuContent>
+    </DropdownMenu>
+  )
+}