feat: i18n support with first translations

tests/engine/i18nRenderLanguage.test.ts

@@ -0,0 +1,26 @@
+import { describe, expect, it } from 'vitest';
+import {
+  resolveSupportedRenderLanguage,
+  resolveRenderLanguageFromProjectPreferences,
+  translateRender,
+} from '../../src/main/shared/i18n';
+
+describe('render i18n', () => {
+  it('resolves rendering language from project preferences', () => {
+    expect(resolveRenderLanguageFromProjectPreferences('de')).toBe('de');
+    expect(resolveRenderLanguageFromProjectPreferences('fr-CA')).toBe('fr');
+    expect(resolveRenderLanguageFromProjectPreferences(undefined)).toBe('en');
+  });
+
+  it('normalizes render language values', () => {
+    expect(resolveSupportedRenderLanguage('it')).toBe('it');
+    expect(resolveSupportedRenderLanguage('es-AR')).toBe('es');
+    expect(resolveSupportedRenderLanguage('')).toBe('en');
+  });
+
+  it('translates render keys with fallback', () => {
+    expect(translateRender('de', 'render.pagination.newer')).toBe('neuer');
+    expect(translateRender('es', 'render.pagination.older')).toBe('más antiguo');
+    expect(translateRender('fr', 'missing.key')).toBe('missing.key');
+  });
+});