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/components/theme-toggle.tsx

@@ -1,4 +1,5 @@
 import { ChevronDown, Lightbulb, LightbulbOff, Monitor, Moon, Sun } from "lucide-react";
+import { useTranslation } from "react-i18next";
 import { Button } from "@/components/ui/button";
 import {
   DropdownMenu,
@@ -11,6 +12,7 @@ import {
 import { useTheme, type Theme } from "@/hooks/use-theme";
 
 export function ThemeToggle() {
+  const { t } = useTranslation();
   const { theme, setTheme, resolvedTheme } = useTheme();
   const isDark = resolvedTheme === "dark";
 
@@ -25,8 +27,8 @@ export function ThemeToggle() {
         size="icon"
         className="h-9 w-9"
         onClick={quickToggle}
-        title={isDark ? "Switch to light theme" : "Switch to dark theme"}
-        aria-label={isDark ? "Switch to light theme" : "Switch to dark theme"}
+        title={isDark ? t("theme.switchLight") : t("theme.switchDark")}
+        aria-label={isDark ? t("theme.switchLight") : t("theme.switchDark")}
         data-testid="button-theme-quick-toggle"
       >
         {isDark ? <Lightbulb className="w-4 h-4" /> : <LightbulbOff className="w-4 h-4" />}
@@ -37,27 +39,27 @@ export function ThemeToggle() {
             variant="ghost"
             size="icon"
             className="h-9 w-9"
-            aria-label="Choose theme"
-            title="Choose theme"
+            aria-label={t("theme.chooseTitle")}
+            title={t("theme.chooseTitle")}
             data-testid="button-theme-menu"
           >
             <ChevronDown className="w-4 h-4" />
           </Button>
         </DropdownMenuTrigger>
         <DropdownMenuContent align="end" sideOffset={6}>
-          <DropdownMenuLabel>Theme</DropdownMenuLabel>
+          <DropdownMenuLabel>{t("theme.title")}</DropdownMenuLabel>
           <DropdownMenuRadioGroup value={theme} onValueChange={(v) => setTheme(v as Theme)}>
             <DropdownMenuRadioItem value="light">
               <Sun className="w-4 h-4 mr-2" />
-              Light
+              {t("theme.light")}
             </DropdownMenuRadioItem>
             <DropdownMenuRadioItem value="dark">
               <Moon className="w-4 h-4 mr-2" />
-              Dark
+              {t("theme.dark")}
             </DropdownMenuRadioItem>
             <DropdownMenuRadioItem value="system">
               <Monitor className="w-4 h-4 mr-2" />
-              System
+              {t("theme.system")}
             </DropdownMenuRadioItem>
           </DropdownMenuRadioGroup>
         </DropdownMenuContent>