feat(i18n): full app + docs localization (de/en)

- translate remaining pages/components (admin, analytics, redundancy,
  trash, compare, browse, watchlist, admin tools tab, category combobox,
  theme toggle, tool preview card, tool-new/edit) to t() calls
- locales: 453 keys each, parity verified
- docs: bilingual handbook + release notes via *.en.md variants,
  language-aware docs.tsx (markdown paths, nav titles, search index),
  LanguageSwitcher in docs header
- generate-docs: emit per-locale handbook/release/search output,
  localized index.json fields (fileEn/titleEn), en-aware snapshots

artifacts/toolrate/src/pages/docs.tsx

@@ -8,6 +8,7 @@ import { Badge } from "@/components/ui/badge";
 import { Input } from "@/components/ui/input";
 import { Button } from "@/components/ui/button";
 import { ThemeToggle } from "@/components/theme-toggle";
+import { LanguageSwitcher } from "@/components/language-switcher";
 import {
   Select,
   SelectContent,
@@ -57,6 +58,20 @@ function docsFile(version: string | null, relPath: string) {
   return version === null ? relPath : `versions/${version}/${relPath}`;
 }
 
+// Prefer the English file/title variant when the active UI language is English.
+function useDocsLocale() {
+  const { i18n } = useTranslation();
+  return (i18n.language ?? "en").toLowerCase().startsWith("en") ? "en" : "de";
+}
+
+function localizedFile(file: string, fileEn: string | null, locale: "en" | "de"): string {
+  return locale === "en" && fileEn ? fileEn : file;
+}
+
+function localizedTitle(title: string, titleEn: string | null, locale: "en" | "de"): string {
+  return locale === "en" && titleEn ? titleEn : title;
+}
+
 // ---------------------------------------------------------------------------
 // Types
 // ---------------------------------------------------------------------------
@@ -100,13 +115,22 @@ type Reference = { tags: TagGroup[]; schemas: SchemaModel[] };
 type ReleaseDoc = {
   version: string;
   file: string;
+  fileEn: string | null;
   title: string;
+  titleEn: string | null;
   date: string | null;
   hasReference: boolean;
   hasHandbook: boolean;
 };
 
-type HandbookPage = { slug: string; file: string; title: string; order: number };
+type HandbookPage = {
+  slug: string;
+  file: string;
+  fileEn: string | null;
+  title: string;
+  titleEn: string | null;
+  order: number;
+};
 
 type SearchEntry = { title: string; href: string; kind: string; text: string };
 
@@ -339,6 +363,7 @@ function DocsNav({
 }) {
   const [location] = useLocation();
   const { t } = useTranslation();
+  const locale = useDocsLocale();
 
   const navLink = (href: string) => {
     const active = location === href || (href !== "/docs" && location.startsWith(href));
@@ -353,7 +378,7 @@ function DocsNav({
       icon: BookOpen,
       items: handbook.map((p) => ({
         href: docsHref(version, `handbook/${p.slug}`),
-        label: p.title,
+        label: localizedTitle(p.title, p.titleEn, locale),
         active: navLink(docsHref(version, `handbook/${p.slug}`)),
       })),
     });
@@ -536,7 +561,7 @@ function FieldTable({ fields }: { fields: Field[] }) {
               </td>
               <td className="px-3 py-2">
                 {f.required ? (
-                  <Badge className="bg-primary/10 text-primary border-primary/20">required</Badge>
+                  <Badge className="bg-primary/10 text-primary border-primary/20">{t("docs.required")}</Badge>
                 ) : (
                   <span className="text-muted-foreground">–</span>
                 )}
@@ -611,8 +636,8 @@ function EndpointTagView({ tag }: { tag: TagGroup }) {
                   <table className="w-full text-sm">
                     <thead>
                       <tr className="border-b bg-muted/50 text-left text-xs uppercase tracking-wider text-muted-foreground">
-                        <th className="px-3 py-2 font-semibold">Name</th>
-                        <th className="px-3 py-2 font-semibold">In</th>
+                        <th className="px-3 py-2 font-semibold">{t("docs.name")}</th>
+                        <th className="px-3 py-2 font-semibold">{t("docs.in")}</th>
                         <th className="px-3 py-2 font-semibold">{t("docs.type")}</th>
                         <th className="px-3 py-2 font-semibold">{t("docs.required")}</th>
                         <th className="px-3 py-2 font-semibold">{t("docs.description")}</th>
@@ -625,7 +650,7 @@ function EndpointTagView({ tag }: { tag: TagGroup }) {
                           <td className="px-3 py-1.5 text-muted-foreground">{p.in}</td>
                           <td className="px-3 py-1.5"><FieldTypeChip type={p.type} /></td>
                           <td className="px-3 py-1.5">
-                            {p.required ? <Badge className="bg-primary/10 text-primary border-primary/20">req</Badge> : "–"}
+                            {p.required ? <Badge className="bg-primary/10 text-primary border-primary/20">{t("docs.required")}</Badge> : "–"}
                           </td>
                           <td className="px-3 py-1.5 text-muted-foreground">
                             {p.description}
@@ -642,7 +667,7 @@ function EndpointTagView({ tag }: { tag: TagGroup }) {
             {ep.requestBody && (
               <div className="mb-3 rounded-lg border bg-muted/30 p-3">
                 <p className="mb-1 text-xs font-semibold uppercase tracking-wider text-muted-foreground">
-                  Request Body {ep.requestBody.required && <Badge className="ml-1">required</Badge>}
+                  {t("docs.requestBody")} {ep.requestBody.required && <Badge className="ml-1">{t("docs.required")}</Badge>}
                 </p>
                 <FieldTypeChip type={ep.requestBody.schema} />
               </div>
@@ -679,6 +704,7 @@ function EndpointTagView({ tag }: { tag: TagGroup }) {
 function ReleasesView({ versions }: { versions: ReleaseDoc[] }) {
   const [, setLocation] = useLocation();
   const { t } = useTranslation();
+  const locale = useDocsLocale();
   return (
     <div className="flex flex-col lg:flex-row gap-8">
       <div className="flex-1 min-w-0 max-w-3xl space-y-4">
@@ -697,7 +723,7 @@ function ReleasesView({ versions }: { versions: ReleaseDoc[] }) {
               <FileText className="h-4 w-4 shrink-0 text-primary" />
               <div className="min-w-0 flex-1">
                 <div className="flex items-center gap-2">
-                  <span className="font-semibold">{v.title}</span>
+                  <span className="font-semibold">{localizedTitle(v.title, v.titleEn, locale)}</span>
                   <Badge variant="secondary">{v.version}</Badge>
                 </div>
                 {v.date && (
@@ -707,7 +733,7 @@ function ReleasesView({ versions }: { versions: ReleaseDoc[] }) {
                   </span>
                 )}
               </div>
-              {v.hasReference && <Badge className="bg-primary/10 text-primary">API-Referenz</Badge>}
+              {v.hasReference && <Badge className="bg-primary/10 text-primary">{t("docs.reference")}</Badge>}
             </button>
           ))}
         </div>
@@ -717,7 +743,9 @@ function ReleasesView({ versions }: { versions: ReleaseDoc[] }) {
   );
 }
 
-function ReleaseNoteView({ version }: { version: string }) {
+function ReleaseNoteView({ version, doc }: { version: string; doc: ReleaseDoc | null }) {
+  const locale = useDocsLocale();
+  const file = doc ? `releases/${localizedFile(doc.file, doc.fileEn, locale)}` : `releases/${version}.md`;
   return (
     <div className="flex flex-col lg:flex-row gap-8">
       <div className="flex-1 min-w-0 max-w-3xl">
@@ -733,16 +761,20 @@ function ReleaseNoteView({ version }: { version: string }) {
             <ExternalLink className="h-3.5 w-3.5" />
           </a>
         </div>
-        <MarkdownView file={`releases/${version}.md`} />
+        <MarkdownView file={file} />
       </div>
     </div>
   );
 }
 
-function HandbookView({ slug }: { slug: string }) {
+function HandbookView({ slug, pages }: { slug: string; pages: HandbookPage[] | null }) {
   const version = useDocsVersion();
-  const handbookFile = `${slug}.md`;
-  return <MarkdownView file={docsFile(version, `handbook/${handbookFile}`)} />;
+  const locale = useDocsLocale();
+  const page = pages?.find((p) => p.slug === slug);
+  const file = page
+    ? docsFile(version, `handbook/${localizedFile(page.file, page.fileEn, locale)}`)
+    : docsFile(version, `handbook/${slug}.md`);
+  return <MarkdownView file={file} />;
 }
 
 // ---------------------------------------------------------------------------
@@ -750,7 +782,9 @@ function HandbookView({ slug }: { slug: string }) {
 // ---------------------------------------------------------------------------
 
 function useDocsSearch(query: string) {
-  const { data, error } = useJson<SearchEntry[]>(query ? `${DOCS_BASE}/search.json` : null);
+  const locale = useDocsLocale();
+  const indexFile = locale === "en" ? "search.en.json" : "search.json";
+  const { data, error } = useJson<SearchEntry[]>(query ? `${DOCS_BASE}/${indexFile}` : null);
   const results = useMemo(() => {
     if (!query.trim() || !data) return [];
     const q = query.trim().toLowerCase();
@@ -879,21 +913,21 @@ export default function Docs() {
   if (version !== null && path.length === 0) {
     content =
       handbook && handbook.length > 0 ? (
-        <HandbookView slug={handbook[0].slug} />
+        <HandbookView slug={handbook[0].slug} pages={handbook} />
       ) : (
-        <ReleaseNoteView version={version} />
+        <ReleaseNoteView version={version} doc={activeRelease} />
       );
   } else if (section === "home") {
     content =
       handbook && handbook.length > 0 ? (
-        <HandbookView slug={handbook[0].slug} />
+        <HandbookView slug={handbook[0].slug} pages={handbook} />
       ) : releases && releases.length > 0 ? (
         <ReleasesView versions={releases} />
       ) : (
         <p className="text-sm text-muted-foreground">{t("docs.noDocs")}</p>
       );
   } else if (section === "handbook" && param) {
-    content = <HandbookView slug={param} />;
+    content = <HandbookView slug={param} pages={handbook} />;
   } else if (section === "reference" && param === "endpoints" && path[2]) {
     const tag = reference?.tags.find(
       (tg) => tg.name.toLowerCase() === path[2].toLowerCase(),
@@ -963,7 +997,7 @@ export default function Docs() {
       </div>
     );
   } else if (section === "releases" && param) {
-    content = <ReleaseNoteView version={param} />;
+    content = <ReleaseNoteView version={param} doc={releases?.find((r) => r.version === param) ?? null} />;
   } else if (section === "releases") {
     content = releases ? <ReleasesView versions={releases} /> : <Skeleton className="h-64 w-full" />;
   } else {
@@ -1014,6 +1048,7 @@ export default function Docs() {
               </Link>
             </div>
             <div className="flex items-center gap-1.5 shrink-0">
+              <LanguageSwitcher />
               <ThemeToggle />
             </div>
           </div>