Add Kannada (ಕನ್ನಡ) language translation support

- Add frontend Kannada translations (src/locales/kn.json)
- Add backend Kannada locale text items (pkg/locales/kn.go)
- Update frontend language configuration (src/locales/index.ts)
- Update backend language registry (pkg/locales/all_locales.go)

Language code: kn (Kannada, ISO 639-1)
Display name: ಕನ್ನಡ
Text direction: ltr (left-to-right)

src/locales/index.ts

@@ -4,6 +4,7 @@ import es from './es.json';
 import fr from './fr.json';
 import it from './it.json';
 import ja from './ja.json';
+import kn from './kn.json';
 import ko from './ko.json';
 import nl from './nl.json';
 import ru from './ru.json';
@@ -75,6 +76,13 @@ export const ALL_LANGUAGES: Record<string, LanguageInfo> = {
         textDirection: 'ltr',
         content: ja
     },
+    'kn': {
+        name: 'Kannada',
+        displayName: 'ಕನ್ನಡ',
+        alternativeLanguageTag: 'kn-IN',
+        textDirection: 'ltr',
+        content: kn
+    },
     'ko': {
         name: 'Korean',
         displayName: '한국어',