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/ui/difficulty-badge.tsx

@@ -0,0 +1,47 @@
+import React from "react"
+import { Sparkles, Wrench, Zap } from "lucide-react"
+import { cn } from "@/lib/utils"
+
+export type Difficulty = "beginner" | "intermediate" | "advanced"
+
+interface DifficultyBadgeProps {
+  level: Difficulty
+  className?: string
+}
+
+const levelConfig: Record<
+  Difficulty,
+  { label: string; style: string; Icon: React.ComponentType<{ className?: string }> }
+> = {
+  beginner: {
+    label: "Beginner",
+    style: "bg-emerald-100 text-emerald-800 border-emerald-200",
+    Icon: Sparkles,
+  },
+  intermediate: {
+    label: "Intermediate",
+    style: "bg-amber-100 text-amber-800 border-amber-200",
+    Icon: Wrench,
+  },
+  advanced: {
+    label: "Advanced",
+    style: "bg-red-100 text-red-800 border-red-200",
+    Icon: Zap,
+  },
+}
+
+export const DifficultyBadge: React.FC<DifficultyBadgeProps> = ({ level, className }) => {
+  const { label, style, Icon } = levelConfig[level]
+  return (
+    <span
+      className={cn(
+        "inline-flex items-center gap-1.5 rounded-full border px-2.5 py-0.5 text-xs font-medium",
+        style,
+        className,
+      )}
+    >
+      <Icon className="h-3.5 w-3.5" aria-hidden="true" />
+      {label}
+    </span>
+  )
+}