Add context menu for vault actions and trash functionality

- Add UiButtonContext component for context menu support on buttons
- Implement vault trash functionality using trash crate
- Move vaults to system trash on desktop (with fallback to permanent delete on mobile)
- Add context menu to vault list items for better mobile UX
- Keep hover delete button for desktop users

src/components/ui/button/context.vue

@@ -0,0 +1,28 @@
+<template>
+  <UContextMenu :items="contextMenuItems">
+    <UiButton
+      v-bind="$attrs"
+      @click="$emit('click', $event)"
+    >
+      <template
+        v-for="(_, slotName) in $slots"
+        #[slotName]="slotProps"
+      >
+        <slot
+          :name="slotName"
+          v-bind="slotProps"
+        />
+      </template>
+    </UiButton>
+  </UContextMenu>
+</template>
+
+<script setup lang="ts">
+import type { ContextMenuItem } from '@nuxt/ui'
+
+defineProps<{
+  contextMenuItems: ContextMenuItem[]
+}>()
+
+defineEmits<{ click: [Event] }>()
+</script>