Upgrade to Vite 8 and Tailwind CSS 4 (#595)

- Vite 6 → 8 (Rolldown bundler), laravel-vite-plugin 1 → 3, @vitejs/plugin-vue 5 → 6
- Tailwind CSS 3 → 4 with CSS-based config (@theme, @plugin, @utility)
- Add @tailwindcss/vite plugin, remove postcss/autoprefixer/sass
- Convert SCSS files to plain CSS (resources/sass → resources/css)
- Migrate tailwind.config.js to CSS @theme directives
- Rename deprecated utility classes (shadow-sm→shadow-xs, outline-none→outline-hidden,
  rounded-sm→rounded-xs, bg-gradient-to→bg-linear-to, ring→ring-3)
- Migrate opacity utilities to color modifiers (bg-opacity, text-opacity,
  border-opacity, ring-opacity → color/N syntax)
- Update primary color CSS vars to full rgb() values for TW4 color-mix()
- Fix border-l color specificity for sidebar navigation (TW4 default border
  color changed from gray-200 to currentColor)
- Fix invalid border color classes (border-grey-light, border-modal-bg, border--200)
- Add @reference directive for @apply in Vue component style blocks
- Convert Vue component <style lang="scss"> blocks to plain CSS

resources/scripts/admin/layouts/LayoutLogin.vue

@@ -168,5 +168,5 @@ const loginPageLogo = computed(() => {
 })
 </script>
 
-<style lang="scss" scoped>
+<style scoped>
 </style>

resources/scripts/admin/layouts/partials/TheSiteHeader.vue

@@ -12,7 +12,7 @@
       px-4
       py-3
       md:h-16 md:px-8
-      bg-gradient-to-r
+      bg-linear-to-r
       from-primary-500
       to-primary-400
     "

resources/scripts/admin/layouts/partials/TheSiteSidebar.vue

@@ -15,7 +15,7 @@
         leave-from="opacity-100"
         leave-to="opacity-0"
       >
-        <DialogOverlay class="fixed inset-0 bg-gray-600 bg-opacity-75" />
+        <DialogOverlay class="fixed inset-0 bg-gray-600/75" />
       </TransitionChild>
 
       <TransitionChild
@@ -47,7 +47,7 @@
                   h-10
                   ml-1
                   rounded-full
-                  focus:outline-none
+                  focus:outline-hidden
                   focus:ring-2
                   focus:ring-inset
                   focus:ring-white
@@ -82,9 +82,9 @@
                 :to="item.link"
                 :class="[
                   hasActiveUrl(item.link)
-                    ? 'text-primary-500 border-primary-500 bg-gray-100 '
-                    : 'text-black',
-                  'cursor-pointer px-0 pl-4 py-3 border-transparent flex items-center border-l-4 border-solid text-sm not-italic font-medium',
+                    ? 'text-primary-500 border-l-primary-500 bg-gray-100 '
+                    : 'text-black border-l-transparent',
+                  'cursor-pointer px-0 pl-4 py-3 flex items-center border-l-4 border-solid text-sm not-italic font-medium',
                 ]"
                 @click="globalStore.setSidebarVisibility(false)"
               >
@@ -136,8 +136,8 @@
         :to="item.link"
         :class="[
           hasActiveUrl(item.link)
-            ? 'text-primary-500 border-primary-500 bg-gray-100 '
-            : 'text-black',
+            ? 'text-primary-500 border-l-primary-500 bg-gray-100 '
+            : 'text-black border-l-transparent',
           'cursor-pointer px-0 pl-6 hover:bg-gray-50 py-3 group flex items-center border-l-4 border-solid text-sm not-italic font-medium',
         ]"
       >