docs: add advanced skills for Vitest, Pinia, and Vue built-ins

Add comprehensive reference documentation for:
- Vitest: environments, projects/workspaces, type testing, vi utilities
- Pinia: HMR, Nuxt integration, SSR setup
- Vue: built-in components (Transition, Teleport, Suspense, KeepAlive) and advanced directives

.agents/skills/vueuse-functions/references/useParentElement.md

@@ -0,0 +1,54 @@
+---
+category: Elements
+---
+
+# useParentElement
+
+Get parent element of the given element
+
+## Usage
+
+When no argument is passed, it will return the parent element of the current component.
+
+```vue
+<script setup lang="ts">
+import { useParentElement } from '@vueuse/core'
+
+const parentEl = useParentElement()
+
+onMounted(() => {
+  console.log(parentEl.value)
+})
+</script>
+```
+
+It can also accept a `ref` as the first argument.
+
+```vue
+<script setup lang="ts">
+import { useParentElement } from '@vueuse/core'
+import { useTemplateRef } from 'vue'
+
+const tooltip = useTemplateRef('tooltip')
+
+const tooltipWrapper = useParentElement(tooltip)
+
+onMounted(() => {
+  console.log(tooltipWrapper.value)
+})
+</script>
+
+<template>
+  <div>
+    <p ref="tooltip" />
+  </div>
+</template>
+```
+
+## Type Declarations
+
+```ts
+export declare function useParentElement(
+  element?: MaybeRefOrGetter<HTMLElement | SVGElement | null | undefined>,
+): Readonly<ShallowRef<HTMLElement | SVGElement | null | undefined>>
+```