[style] unify Vue widget/slot label colors (#6149)

## Summary

Change labels on all widgets and slots to the same value which matches
design spec.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6149-style-unify-Vue-widget-slot-label-colors-2916d73d3650810a98f3ee75e0b22da0)
by [Unito](https://www.unito.io)

---------

Co-authored-by: DrJKL <DrJKL0424@gmail.com>

src/renderer/extensions/vueNodes/widgets/components/form/FormSelectButton.test.ts

@@ -313,7 +313,7 @@ describe('FormSelectButton Core Component', () => {
       const buttons = wrapper.findAll('button')
       expect(buttons[0].classes()).not.toContain('bg-white') // Selected styling disabled
       expect(buttons[0].classes()).toContain('opacity-50')
-      expect(buttons[0].classes()).toContain('text-zinc-500')
+      expect(buttons[0].classes()).toContain('text-secondary')
     })
   })
 
@@ -372,7 +372,7 @@ describe('FormSelectButton Core Component', () => {
 
       const unselectedButton = wrapper.findAll('button')[1]
       expect(unselectedButton.classes()).toContain('bg-transparent')
-      expect(unselectedButton.classes()).toContain('text-zinc-500')
+      expect(unselectedButton.classes()).toContain('text-secondary')
     })
 
     it('applies hover effects to enabled unselected buttons', () => {

src/renderer/extensions/vueNodes/widgets/components/form/FormSelectButton.vue

@@ -21,10 +21,9 @@
             'opacity-50 cursor-not-allowed': disabled,
             'cursor-pointer': !disabled
           },
-          {
-            'text-neutral-900': isSelected(option) && !disabled,
-            'text-zinc-500': !isSelected(option) || disabled
-          }
+          isSelected(option) && !disabled
+            ? 'text-neutral-900'
+            : 'text-secondary'
         )
       "
       :disabled="disabled"

src/renderer/extensions/vueNodes/widgets/components/form/dropdown/FormDropdownMenuActions.vue

@@ -44,7 +44,7 @@ function handleSortSelected(item: SortOption) {
 </script>
 
 <template>
-  <div class="flex gap-2 px-4 text-zinc-400">
+  <div class="text-secondary flex gap-2 px-4">
     <label
       :class="
         cn(