Fix literal \n characters appearing in proof analysis feedback

Gemini sometimes returns the literal two-character sequence \n instead of
a real newline in agent feedback text. This caused "Recommendation:" to
appear on the same line as "Issue:" with visible \n characters. Adding a
normalization step at the start of formatFeedbackText converts literal \n
sequences to real newlines so the existing line-splitting logic handles
them correctly.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/components/FeedbackReport.tsx

@@ -41,6 +41,8 @@ const formatFeedbackText = (text: string): React.ReactNode => {
 
     // First, handle HTML tags by converting them to a normalized format
     let normalizedText = text
+        // Convert literal \n sequences to real newlines
+        .replace(/\\n/g, '\n')
         // Replace </li> and </ul> with newlines
         .replace(/<\/li>/gi, '\n')
         .replace(/<\/ul>/gi, '\n')