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/css/components/pace-loader.css

@@ -0,0 +1,56 @@
+.pace {
+  -webkit-pointer-events: none;
+  pointer-events: none;
+  -webkit-user-select: none;
+  -moz-user-select: none;
+  user-select: none;
+}
+
+.pace-inactive {
+  display: none;
+}
+
+.pace .pace-progress {
+  background: #3f39ad;
+  position: fixed;
+  z-index: 2000;
+  top: 0;
+  right: 100%;
+  width: 100%;
+  height: 2px;
+}
+
+.pace .pace-progress-inner {
+  display: block;
+  position: absolute;
+  right: 0px;
+  width: 100px;
+  height: 100%;
+  box-shadow: 0 0 10px #5851d8, 0 0 5px #5851d8;
+  opacity: 1;
+  transform: rotate(3deg) translate(0px, -4px);
+}
+
+.pace .pace-activity {
+  display: block;
+  position: fixed;
+  z-index: 2000;
+  top: 15px;
+  right: 15px;
+  width: 14px;
+  height: 14px;
+  border: solid 2px transparent;
+  border-top-color: #5851d8;
+  border-left-color: #5851d8;
+  border-radius: 10px;
+  animation: pace-spinner 400ms linear infinite;
+}
+
+@keyframes pace-spinner {
+  0% {
+    transform: rotate(0deg);
+  }
+  100% {
+    transform: rotate(360deg);
+  }
+}