feat(i18n): add Turkish (tr) translation (#1571)

frontend/scripts/check-i18n-parity.mjs

@@ -319,6 +319,19 @@ const ES_COGNATES = [
   'Avery 5160 — US Letter sheet (25.4 × 66.7 mm × 30)',
 ];
 
+// Turkish cognates — technical UI labels that Turkish speakers use verbatim
+// from English (loanwords + acronyms + format strings). Curated, not a shortcut.
+const TR_COGNATES = [
+  'Filament', 'Firmware', 'Disk', 'Hex', 'Test', 'Port', 'Model', 'Metal',
+  'Min', 'Normal', 'Platform', 'Net', 'Trend', 'Commit', 'Global', 'Proxy',
+  'N/A', 'email',
+  'STARTTLS (Port 587)', 'SSL/TLS (Port 465)',
+  '({{count}}/8)', 'Hex: #{{hex}}', 'MakerWorld: {{designer}}',
+  '{{count}} filament', '{{printer}}: {{error}}', '{{weight}}g',
+  'Filament {{index}} ({{type}})',
+  'EC984C,#6CD4BC,A66EB9,D87694',
+];
+
 const IDENTICAL_TO_EN_ALLOWED = {
   de: new Set(DE_COGNATES),
   fr: new Set(FR_COGNATES),
@@ -329,6 +342,7 @@ const IDENTICAL_TO_EN_ALLOWED = {
   'pt-BR': new Set(PT_BR_COGNATES),
   'zh-CN': new Set(ZH_CN_COGNATES),
   'zh-TW': new Set(ZH_TW_COGNATES),
+  tr: new Set(TR_COGNATES),
 };
 
 // Pure comparison logic, exported so tests can verify each failure mode

frontend/src/i18n/index.ts

@@ -13,6 +13,7 @@ import ko from './locales/ko';
 import ptBR from './locales/pt-BR';
 import zhCN from './locales/zh-CN';
 import zhTW from './locales/zh-TW';
+import tr from './locales/tr';
 
 const resources = {
   en: { translation: en },
@@ -25,6 +26,7 @@ const resources = {
   'pt-BR': { translation: ptBR },
   'zh-CN': { translation: zhCN },
   'zh-TW': { translation: zhTW },
+  tr: { translation: tr },
 };
 
 i18n
@@ -33,7 +35,7 @@ i18n
   .init({
     resources,
     fallbackLng: 'en',
-    supportedLngs: ['en', 'de', 'es', 'fr', 'ja', 'it', 'ko', 'pt-BR', 'zh-CN', 'zh-TW'],
+    supportedLngs: ['en', 'de', 'es', 'fr', 'ja', 'it', 'ko', 'pt-BR', 'tr', 'zh-CN', 'zh-TW'],
 
     detection: {
       // Order of detection methods
@@ -67,4 +69,5 @@ export const availableLanguages = [
   { code: 'pt-BR', name: 'Portuguese (Brazil)', nativeName: 'Português (Brasil)' },
   { code: 'zh-CN', name: 'Chinese (Simplified)', nativeName: '简体中文' },
   { code: 'zh-TW', name: 'Chinese (Traditional)', nativeName: '繁體中文' },
+  { code: 'tr', name: 'Turkish', nativeName: 'Türkçe' },
 ];