[Fix Accessibility] Remove redundant role attribute from sidebar navigation list (#1726)

## Accessibility Improvements and UI Refinements

### File Changes:
1. `sidebar.js` - Removed redundant `role="list"` attribute from sidebar
navigation container
2. `src/mdx/inline-code.js` - Adjusted inline code font size from 85% to
80% for better visual consistency

### Summary:
This PR removes a redundant accessibility role attribute from the
sidebar navigation and fine-tunes inline code styling to improve both
accessibility compliance and visual presentation.

### Screenshots
<img width="732" height="190" alt="image"
src="https://github.com/user-attachments/assets/614eef9d-57b9-4895-9b9a-80e5235f6f2e"
/>
<img width="370" height="310" alt="image"
src="https://github.com/user-attachments/assets/d332fcef-4374-402e-9bb0-6acb2cd4aea3"
/>
<img width="370" height="310" alt="image"
src="https://github.com/user-attachments/assets/9ba9c755-2a9f-4144-86aa-603e5307a6d6"
/>

Author: jpg619

src/components/sidebar.js

@@ -48,7 +48,7 @@ const Sidebar = () => (
         borderColor: 'border.subtle',
       }}
     >
-      <Box sx={{display: 'flex', flexDirection: 'column'}} role="list">
+      <Box sx={{display: 'flex', flexDirection: 'column'}}>
         <NavItems />
       </Box>
     </Box>

src/mdx/code.js

@@ -48,7 +48,7 @@ const ClipboardCopy = ({value, ...props}) => {
 export const InlineCode = styled.code`
   padding: 0.2em 0.4em;
   font-family: ${themeGet('fonts.mono')};
-  font-size: 85%;
+  font-size: 80%;
   background-color: ${themeGet('colors.neutral.muted')};
   border-radius: ${themeGet('radii.2')};
 `