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/doc-header.tsx

@@ -0,0 +1,40 @@
+import React from "react"
+import { SectionBadge } from "./section-badge"
+import { EstimatedTime } from "./estimated-time"
+import { ScriptViewer } from "./script-viewer"
+import { cn } from "@/lib/utils"
+
+interface DocHeaderProps {
+  title: string
+  description?: string
+  section?: string
+  estimatedMinutes?: number
+  scriptPath?: string
+  className?: string
+}
+
+export const DocHeader: React.FC<DocHeaderProps> = ({
+  title,
+  description,
+  section,
+  estimatedMinutes,
+  scriptPath,
+  className,
+}) => {
+  const hasBadges = section || estimatedMinutes || scriptPath
+  return (
+    <header className={cn("mb-8", className)}>
+      <h1 className="text-3xl font-bold text-gray-900 mb-2">{title}</h1>
+      {hasBadges && (
+        <div className="flex flex-wrap items-center gap-2 mb-3">
+          {section && <SectionBadge section={section} />}
+          {estimatedMinutes !== undefined && <EstimatedTime minutes={estimatedMinutes} />}
+          {scriptPath && <ScriptViewer scriptPath={scriptPath} />}
+        </div>
+      )}
+      {description && (
+        <p className="text-gray-700 leading-relaxed m-0">{description}</p>
+      )}
+    </header>
+  )
+}