docs(design): update design system specifications and component styles

- remove color palette table from main color section in DESIGN.md
- update typography scale (reduce body/secondary text sizes)
- revise border radius values for badges, buttons, modals, and cards
- expand sidebar navigation section with detailed structure and visual states
- add accordion section behavior and item template specs
- update Badge component to use fully rounded corners and adjust sizing
- update Modal component border radius and backdrop styles

src/shared/components/Badge.js

@@ -25,9 +25,9 @@ const Badge = ({
     };
 
     const sizes = {
-        sm: 'px-[8px] py-[2px] rounded-lg text-[11px]',
-        md: 'px-[8px] py-[2px] rounded-lg text-[11px]',
-        lg: 'px-3 py-1 rounded-lg text-xs'
+        sm: 'px-[8px] py-[2px] rounded-full text-[11px]',
+        md: 'px-[8px] py-[2px] rounded-full text-[11px]',
+        lg: 'px-3 py-1 rounded-full text-xs'
     };
 
     const variantClass = color ? '' : (variants[variant] || variants.default);

src/shared/components/Modal.js

@@ -73,7 +73,7 @@ const Modal = ({
                         w-full ${sizeClasses[size]}
                         bg-white dark:bg-[#0B0B0B]
                         border border-neutral-200 dark:border-neutral-800
-                        rounded-lg
+                        rounded-xl
                         shadow-xl
                         max-h-[90vh]
                         overflow-hidden