feat(playground): enhance SSE debugging and add image paste support with i18n

- Add SSEViewer component for interactive SSE message inspection
  * Display SSE data stream with collapsible panels
  * Show parsed JSON with syntax highlighting
  * Display key information badges (content, tokens, finish reason)
  * Support copy individual or all SSE messages
  * Show error messages with detailed information

- Support Ctrl+V to paste images in chat input
  * Enable image paste in CustomInputRender component
  * Auto-detect and add pasted images to image list
  * Show toast notifications for paste results

- Add complete i18n support for 6 languages
  * Chinese (zh): Complete translations
  * English (en): Complete translations
  * Japanese (ja): Add 28 new translations
  * French (fr): Add 28 new translations
  * Russian (ru): Add 28 new translations
  * Vietnamese (vi): Add 32 new translations

- Update .gitignore to exclude data directory

web/src/components/playground/DebugPanel.jsx

@@ -29,6 +29,7 @@ import {
 import { Code, Zap, Clock, X, Eye, Send } from 'lucide-react';
 import { useTranslation } from 'react-i18next';
 import CodeViewer from './CodeViewer';
+import SSEViewer from './SSEViewer';
 
 const DebugPanel = ({
   debugData,
@@ -180,15 +181,27 @@ const DebugPanel = ({
               <div className='flex items-center gap-2'>
                 <Zap size={16} />
                 {t('响应')}
+                {debugData.sseMessages && debugData.sseMessages.length > 0 && (
+                  <span className='px-1.5 py-0.5 text-xs bg-blue-100 text-blue-600 rounded-full'>
+                    SSE ({debugData.sseMessages.length})
+                  </span>
+                )}
               </div>
             }
             itemKey='response'
           >
-            <CodeViewer
-              content={debugData.response}
-              title='response'
-              language='json'
-            />
+            {debugData.sseMessages && debugData.sseMessages.length > 0 ? (
+              <SSEViewer
+                sseData={debugData.sseMessages}
+                title='response'
+              />
+            ) : (
+              <CodeViewer
+                content={debugData.response}
+                title='response'
+                language='json'
+              />
+            )}
           </TabPane>
         </Tabs>
       </div>