[Fix Accessibility]: Enhance accessibility by adding ARIA attributes to table of content (#1730)
### File Change - `src/components/search-results.js` - Enhanced search result items with descriptive ARIA labels including position and hierarchy information ### BEFORE <img width="471" height="188" alt="image" src="https://github.com/user-attachments/assets/fa5c53fe-7370-4e63-a13b-0cd0cf037f25" /> ### AFTER <img width="453" height="220" alt="image" src="https://github.com/user-attachments/assets/cae92e63-ed31-4d1c-95c1-426c391874d4" /> ### File Change - `src/components/table-of-contents-items.js` - Added ARIA labels to table of contents navigation items and restructured nested navigation with proper SubNav components ### BEFORE <img width="246" height="286" alt="image" src="https://github.com/user-attachments/assets/b02b7341-1dac-414e-927a-264161dfec31" /> <img width="393" height="111" alt="image" src="https://github.com/user-attachments/assets/9b11a6fe-98d4-4390-9960-27c52543ca2f" /> ### AFTER <img width="246" height="286" alt="image" src="https://github.com/user-attachments/assets/397d9b2b-92e5-4429-a1eb-19caf4f5562c" /> <img width="246" height="286" alt="image" src="https://github.com/user-attachments/assets/a769f9ee-42dd-45eb-b912-46688e0091da" /> <img width="414" height="114" alt="image" src="https://github.com/user-attachments/assets/8b06aa24-6700-4e94-af9a-5553ede122e9" /> ### Summary This PR improves accessibility for screen readers by adding descriptive ARIA attributes to search results and table of contents navigation, ensuring users can understand item context and position within the navigation structure.