style(ui): change default button size from sm to md and remove explicit size="sm" props

src/shared/components/Button.js

@@ -7,7 +7,7 @@ const Button = ({
     onClick,
     type = 'button',
     variant = 'primary',
-    size = 'sm',
+    size = 'md',
     disabled = false,
     loading = false,
     icon,
@@ -27,23 +27,23 @@ const Button = ({
     };
 
     const sizes = {
-        sm: 'px-[12px] py-[6px] text-[12px] gap-1.5',
-        md: 'px-[14px] py-[7px] text-[13px] gap-2',
-        lg: 'px-6 py-3 text-base gap-2.5'
+        sm: '',
+        md: 'px-[12px] py-[7px] text-[12px] gap-1.5',
+        lg: ''
     };
 
     const iconOnlySizes = {
-        sm: 'p-[6px] text-[12px]',
-        md: 'p-[7px] text-[13px]',
-        lg: 'p-3 text-base'
+        sm: '',
+        md: 'p-[7px] text-[12px]',
+        lg: ''
     };
 
     const isIconOnly = icon && !children;
     
     const iconSizes = {
-        sm: 'w-3.5 h-3.5',
+        sm: '',
         md: 'w-4 h-4',
-        lg: 'w-5 h-5'
+        lg: ''
     };
 
     const LoadingSpinner = () => (