Migración a shadcn-vue + Tailwind CSS v4

- Tailwind CSS v4 con @tailwindcss/vite
- shadcn-vue: 19 componentes UI (button, card, dialog, table, select,
  tabs, sidebar, separator, breadcrumb, badge, avatar, dropdown-menu,
  tooltip, input, switch, sheet, skeleton)
- Sidebar collapsible con íconos Lucide
- Theme Teloprax en CSS variables (rojo #E63946, negro #1A1A2E)
- LoginView, DashboardView, CalendarView, SchedulerView migrados
- Eliminado AppShell.vue manual (reemplazado por SidebarProvider)
- Layout con breadcrumb, sidebar trigger, header unificado

src/components/ui/dropdown-menu/DropdownMenu.vue

@@ -0,0 +1,19 @@
+<script setup lang="ts">
+import type { DropdownMenuRootEmits, DropdownMenuRootProps } from 'reka-ui'
+import { DropdownMenuRoot, useForwardPropsEmits } from 'reka-ui'
+
+const props = defineProps<DropdownMenuRootProps>()
+const emits = defineEmits<DropdownMenuRootEmits>()
+
+const forwarded = useForwardPropsEmits(props, emits)
+</script>
+
+<template>
+  <DropdownMenuRoot
+    v-slot="slotProps"
+    data-slot="dropdown-menu"
+    v-bind="forwarded"
+  >
+    <slot v-bind="slotProps" />
+  </DropdownMenuRoot>
+</template>