✨ Add i18n support

frontend/src/i18n/locales/en-US.ts

@@ -0,0 +1,33 @@
+export default {
+  toolbar: {
+    editor: {
+      lines: 'Ln',
+      characters: 'Ch',
+      selected: 'Sel'
+    },
+    fontSize: 'Font Size',
+    fontSizeTooltip: 'Font Size (Ctrl+wheel to adjust)',
+    tabLabel: 'Tab',
+    tabType: {
+      spaces: 'Spaces',
+      tab: 'Tab'
+    },
+    encoding: 'UTF-8',
+    settings: 'Settings'
+  },
+  config: {
+    loadSuccess: 'Configuration loaded successfully',
+    loadFailed: 'Failed to load configuration',
+    saveSuccess: 'Configuration saved',
+    saveFailed: 'Failed to save configuration',
+    resetSuccess: 'Configuration reset to defaults',
+    resetFailed: 'Failed to reset configuration',
+    fontSizeFixed: 'Font size ({value}) has been corrected to {fixed}',
+    tabSizeFixed: 'Tab size ({value}) has been corrected to {fixed}',
+    tabTypeFixed: 'Tab type ({value}) is invalid, corrected to spaces'
+  },
+  languages: {
+    'zh-CN': '简体中文',
+    'en-US': 'English'
+  }
+};