fix: improve mode toggle robustness and add i18n support

- Make mode detection more robust (handle ::1, 0.0.0.0)
- Add getProxyPort() to parse port from ANTHROPIC_BASE_URL dynamically
- Add i18n translation keys for mode toggle in all 5 languages
- Update settings.html to use translation keys and dynamic port

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/webui/index.js

@@ -628,7 +628,12 @@ export function mountWebUI(app, dirname, accountManager) {
             const baseUrl = claudeConfig.env?.ANTHROPIC_BASE_URL || '';
 
             // Determine mode based on ANTHROPIC_BASE_URL
-            const isProxy = baseUrl.includes('localhost') || baseUrl.includes('127.0.0.1');
+            const isProxy = baseUrl && (
+                baseUrl.includes('localhost') ||
+                baseUrl.includes('127.0.0.1') ||
+                baseUrl.includes('::1') ||
+                baseUrl.includes('0.0.0.0')
+            );
 
             res.json({
                 status: 'ok',