feat(feedback): Add content improvement feedback system

Frontend (frontend/app.js):

- Add textarea for improvement feedback

- Add submit button with loading state

- Handle API response and display improved content

Backend (backend/copywriter.py):

- Add improve_copy() method using Cohere API

- Integrate retry mechanism for API calls

Backend (backend/main.py):

- Add /improve-content POST endpoint

- Implement error handling and return improved content with metadata

Testing:

- Verified feedback submission flow

- Confirmed improved content generation

- Tested error scenarios and loading states

frontend/styles.css

@@ -446,9 +446,30 @@ header {
 }
 
 .result-content {
-    padding: 25px;
     white-space: pre-wrap;
+    font-family: var(--font-family);
     line-height: 1.6;
+    padding: 20px;
+    background: white;
+    border-radius: 8px;
+    box-shadow: var(--shadow-sm);
+}
+
+.result-content ul,
+.result-content ol {
+    padding-left: 20px;
+    margin: 1em 0;
+}
+
+.result-content p {
+    margin: 1em 0;
+}
+
+/* Style bullet points */
+.result-content • {
+    margin-left: 1em;
+    display: list-item;
+    list-style-type: disc;
 }
 
 .metadata-panel {
@@ -745,6 +766,48 @@ header {
     margin-top: 10px;
 }
 
+.tag-selector.read-only .tag {
+    cursor: default;
+}
+
+.style-description {
+    margin-top: 15px;
+    font-style: italic;
+    color: var(--grey-600);
+    line-height: 1.6;
+}
+
+.style-note {
+    display: flex;
+    align-items: center;
+    color: var(--grey-600);
+    font-style: italic;
+}
+
+.style-note i {
+    margin-right: 8px;
+    color: var(--grey-500);
+}
+
+.alert {
+    padding: 15px;
+    border-radius: var(--radius-md);
+    margin-top: 15px;
+    display: flex;
+    align-items: center;
+}
+
+.alert i {
+    margin-right: 10px;
+    font-size: 18px;
+}
+
+.alert-info {
+    background-color: rgba(98, 54, 255, 0.1);
+    color: var(--primary-dark);
+    border-left: 4px solid var(--primary-color);
+}
+
 .tag {
     display: inline-flex;
     align-items: center;
@@ -885,40 +948,40 @@ header {
         width: 80px;
         padding: 15px 0;
     }
-    
+
     .logo h2 {
         width: 50px;
         height: 50px;
         font-size: 20px;
     }
-    
+
     .menu li {
         justify-content: center;
         padding: 12px;
     }
-    
+
     .menu li i {
         margin-right: 0;
         font-size: 20px;
     }
-    
+
     .menu li span {
         display: none;
     }
-    
+
     .user-info {
         justify-content: center;
         padding: 10px;
     }
-    
+
     .user-avatar {
         margin-right: 0;
     }
-    
+
     .user-name {
         display: none;
     }
-    
+
     .content {
         margin-left: 80px;
         max-width: calc(100vw - 80px);
@@ -930,35 +993,35 @@ header {
         flex-direction: column;
         gap: 10px;
     }
-    
+
     .templates-grid {
         grid-template-columns: 1fr;
     }
-    
-    .history-item, 
+
+    .history-item,
     .training-item {
         flex-direction: column;
         align-items: flex-start;
     }
-    
+
     .history-item-type,
     .training-item-type {
         margin-bottom: 10px;
     }
-    
+
     .history-item-content,
     .training-item-content {
         padding: 0;
         margin-bottom: 10px;
     }
-    
+
     .history-item-date {
         text-align: left;
         margin-bottom: 10px;
     }
-    
+
     .checkbox-group {
         flex-direction: column;
         gap: 10px;
     }
-}
+}