fix(Kbd): optional value prop when using default slot

src/runtime/components/Kbd.vue

@@ -17,7 +17,7 @@ export interface KbdProps {
    * @defaultValue 'kbd'
    */
   as?: any
-  value: KbdKey | string
+  value?: KbdKey | string
   variant?: KbdVariants['variant']
   size?: KbdVariants['size']
   class?: any

src/runtime/composables/useKbd.ts

@@ -35,7 +35,10 @@ const _useKbd = () => {
     metaSymbol.value = macOS.value ? kbdKeysMap.command : kbdKeysMap.ctrl
   })
 
-  function getKbdKey(value: KbdKey | string) {
+  function getKbdKey(value?: KbdKey | string) {
+    if (!value) {
+      return
+    }
     if (value === 'meta') {
       return metaSymbol.value
     }