FE: Add styled components for JSON formatting UI

Adds new styled components to support JSON formatting functionality:

- ValidationSection: Layout for JSON validation checkbox
- FieldGroup: Wrapper for field label and editor with format button
- FieldHeader: Flex layout for field label and format button
- FormatButton: Compact button styling with accessibility features
- ResizableEditorWrapper: CSS-based resize functionality for headers field
- ValidationError/FormatSuccess: Feedback styling for user interactions
- ScreenReaderOnly: Accessibility helper for screen reader text

Features:
- Responsive design following existing patterns
- Theme-aware styling with proper fallbacks
- Focus management and accessibility compliance
- Visual feedback for formatting state changes
- Enhanced resize handle for better usability

Author: aaron-seq

frontend/src/components/Topics/Topic/SendMessage/SendMessage.styled.tsx

@@ -1,4 +1,5 @@
 import styled from 'styled-components';
+import { Button } from 'components/common/Button/Button';
 
 export const Wrapper = styled.div`
   display: block;
@@ -17,6 +18,7 @@ export const Columns = styled.div`
     display: flex;
   }
 `;
+
 export const Flex = styled.div`
   display: flex;
   flex-direction: row;
@@ -25,6 +27,7 @@ export const Flex = styled.div`
     flex-direction: column;
   }
 `;
+
 export const FlexItem = styled.div`
   width: 18rem;
   @media screen and (max-width: 1450px) {
@@ -34,3 +37,144 @@ export const FlexItem = styled.div`
     width: 100%;
   }
 `;
+
+// New styled components for JSON formatting functionality
+export const ValidationSection = styled.div`
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  margin-bottom: 8px;
+`;
+
+export const FieldGroup = styled.div`
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+`;
+
+export const FieldHeader = styled.div`
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  margin-bottom: 4px;
+`;
+
+export const FormatButton = styled(Button)`
+  font-size: 12px;
+  padding: 4px 8px;
+  height: 24px;
+  min-width: auto;
+  border-radius: 3px;
+  
+  &:focus-visible {
+    outline: 2px solid ${({ theme }) => theme.button.primary.backgroundColor.normal};
+    outline-offset: 2px;
+  }
+  
+  &:disabled {
+    opacity: 0.5;
+    cursor: not-allowed;
+  }
+  
+  // Ensure proper contrast and accessibility
+  &[aria-pressed="true"] {
+    background: ${({ theme }) => theme.button.primary.backgroundColor.active};
+    color: ${({ theme }) => theme.button.primary.color.active};
+  }
+`;
+
+export const ResizableEditorWrapper = styled.div`
+  .ace_editor {
+    resize: vertical !important;
+    min-height: 40px !important;
+    max-height: 200px !important;
+    overflow: auto;
+    border: 1px solid ${({ theme }) => theme.input?.borderColor?.normal || '#ddd'};
+    border-radius: 4px;
+    
+    &:focus-within {
+      border-color: ${({ theme }) => theme.input?.borderColor?.focus || theme.button.primary.backgroundColor.normal};
+      box-shadow: 0 0 0 2px ${({ theme }) => theme.button.primary.backgroundColor.normal}33;
+    }
+  }
+  
+  .ace_content {
+    cursor: text;
+  }
+  
+  .ace_scrollbar-v {
+    right: 0 !important;
+  }
+  
+  .ace_scrollbar-h {
+    bottom: 0 !important;
+  }
+  
+  // Enhanced resize handle visibility
+  .ace_editor::after {
+    content: '';
+    position: absolute;
+    bottom: 0;
+    right: 0;
+    width: 12px;
+    height: 12px;
+    background: linear-gradient(
+      135deg,
+      transparent 0%,
+      transparent 46%,
+      ${({ theme }) => theme.input?.borderColor?.normal || '#ddd'} 46%,
+      ${({ theme }) => theme.input?.borderColor?.normal || '#ddd'} 50%,
+      transparent 50%,
+      transparent 56%,
+      ${({ theme }) => theme.input?.borderColor?.normal || '#ddd'} 56%,
+      ${({ theme }) => theme.input?.borderColor?.normal || '#ddd'} 60%,
+      transparent 60%
+    );
+    cursor: nw-resize;
+    z-index: 10;
+  }
+`;
+
+// Error state styling for validation feedback
+export const ValidationError = styled.div`
+  color: ${({ theme }) => theme.button.danger.backgroundColor.normal};
+  font-size: 12px;
+  margin-top: 4px;
+  display: flex;
+  align-items: center;
+  gap: 4px;
+  
+  &::before {
+    content: '⚠';
+    font-size: 14px;
+  }
+`;
+
+// Success state styling for formatting feedback
+export const FormatSuccess = styled.div`
+  color: ${({ theme }) => theme.button.primary.backgroundColor.normal};
+  font-size: 12px;
+  margin-top: 4px;
+  display: flex;
+  align-items: center;
+  gap: 4px;
+  
+  &::before {
+    content: '✓';
+    font-size: 14px;
+    font-weight: bold;
+  }
+`;
+
+// Accessibility improvements for screen readers
+export const ScreenReaderOnly = styled.span`
+  position: absolute;
+  width: 1px;
+  height: 1px;
+  padding: 0;
+  margin: -1px;
+  overflow: hidden;
+  clip: rect(0, 0, 0, 0);
+  white-space: nowrap;
+  border: 0;
+`;