Add Impressum with attribution + expand language dropdown to 26 languages

Impressum page (/impressum) with rechtskonform attribution for:
- Wiktionary/Kaikki.org (CC BY-SA 3.0 + GFDL) — dictionary data
- ipa-dict (MIT) — IPA phonetic transcriptions
- Wikimedia Commons (CC BY-SA) — vocabulary images
- Piper TTS (MIT) — speech synthesis
- pyspellchecker (MIT) — spell checking

Language dropdown expanded from 7 to 26 European languages:
DE, EN, TR, AR, UK, RU, PL, FR, ES, IT, PT, NL, RO, EL, BG,
HR, CS, HU, SV, DA, FI, SK, SL, LT, LV, ET.

Dropdown now shows full name: "TR — Turkce", "AR — العربية", etc.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

studio-v2/components/learn/LanguageSwitcher.tsx

@@ -10,13 +10,35 @@ interface LanguageSwitcherProps {
 }
 
 const LANGS = [
-  { code: 'de', label: 'DE' },
-  { code: 'en', label: 'EN' },
-  { code: 'tr', label: 'TR' },
-  { code: 'ar', label: 'AR' },
-  { code: 'uk', label: 'UK' },
-  { code: 'ru', label: 'RU' },
-  { code: 'pl', label: 'PL' },
+  // Main languages
+  { code: 'de', label: 'DE', name: 'Deutsch' },
+  { code: 'en', label: 'EN', name: 'English' },
+  // Migration languages
+  { code: 'tr', label: 'TR', name: 'Turkce' },
+  { code: 'ar', label: 'AR', name: 'العربية' },
+  { code: 'uk', label: 'UK', name: 'Українська' },
+  { code: 'ru', label: 'RU', name: 'Русский' },
+  { code: 'pl', label: 'PL', name: 'Polski' },
+  // European languages
+  { code: 'fr', label: 'FR', name: 'Francais' },
+  { code: 'es', label: 'ES', name: 'Espanol' },
+  { code: 'it', label: 'IT', name: 'Italiano' },
+  { code: 'pt', label: 'PT', name: 'Portugues' },
+  { code: 'nl', label: 'NL', name: 'Nederlands' },
+  { code: 'ro', label: 'RO', name: 'Romana' },
+  { code: 'el', label: 'EL', name: 'Ελληνικά' },
+  { code: 'bg', label: 'BG', name: 'Български' },
+  { code: 'hr', label: 'HR', name: 'Hrvatski' },
+  { code: 'cs', label: 'CS', name: 'Cestina' },
+  { code: 'hu', label: 'HU', name: 'Magyar' },
+  { code: 'sv', label: 'SV', name: 'Svenska' },
+  { code: 'da', label: 'DA', name: 'Dansk' },
+  { code: 'fi', label: 'FI', name: 'Suomi' },
+  { code: 'sk', label: 'SK', name: 'Slovencina' },
+  { code: 'sl', label: 'SL', name: 'Slovenscina' },
+  { code: 'lt', label: 'LT', name: 'Lietuviu' },
+  { code: 'lv', label: 'LV', name: 'Latviesu' },
+  { code: 'et', label: 'ET', name: 'Eesti' },
 ]
 
 /**
@@ -33,7 +55,7 @@ export function LanguageSwitcher({ currentLang, onLangChange, isDark, compact =
           isDark ? 'bg-white/10 text-white/70' : 'bg-slate-100 text-slate-600'
         }`}
       >
-        {LANGS.map(l => <option key={l.code} value={l.code}>{l.label}</option>)}
+        {LANGS.map(l => <option key={l.code} value={l.code}>{l.label} — {l.name}</option>)}
       </select>
     )
   }