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/useDisplayMedia.md

@@ -0,0 +1,67 @@
+---
+category: Sensors
+related: useUserMedia
+---
+
+# useDisplayMedia
+
+Reactive [`mediaDevices.getDisplayMedia`](https://developer.mozilla.org/en-US/docs/Web/API/MediaDevices/getDisplayMedia) streaming.
+
+## Usage
+
+```vue
+<script setup lang="ts">
+import { useDisplayMedia } from '@vueuse/core'
+import { useTemplateRef } from 'vue'
+
+const { stream, start } = useDisplayMedia()
+
+// start streaming
+start()
+
+const videoRef = useTemplateRef('video')
+watchEffect(() => {
+  // preview on a video element
+  videoRef.value.srcObject = stream.value
+})
+</script>
+
+<template>
+  <video ref="video" />
+</template>
+```
+
+## Type Declarations
+
+```ts
+export interface UseDisplayMediaOptions extends ConfigurableNavigator {
+  /**
+   * If the stream is enabled
+   * @default false
+   */
+  enabled?: MaybeRef<boolean>
+  /**
+   * If the stream video media constraints
+   */
+  video?: boolean | MediaTrackConstraints | undefined
+  /**
+   * If the stream audio media constraints
+   */
+  audio?: boolean | MediaTrackConstraints | undefined
+}
+export interface UseDisplayMediaReturn extends Supportable {
+  stream: ShallowRef<MediaStream | undefined>
+  start: () => Promise<MediaStream | undefined>
+  stop: () => void
+  enabled: ShallowRef<boolean>
+}
+/**
+ * Reactive `mediaDevices.getDisplayMedia` streaming
+ *
+ * @see https://vueuse.org/useDisplayMedia
+ * @param options
+ */
+export declare function useDisplayMedia(
+  options?: UseDisplayMediaOptions,
+): UseDisplayMediaReturn
+```