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/useEyeDropper.md

@@ -0,0 +1,72 @@
+---
+category: Browser
+---
+
+# useEyeDropper
+
+Reactive [EyeDropper API](https://developer.mozilla.org/en-US/docs/Web/API/EyeDropper_API)
+
+## Usage
+
+```ts
+import { useEyeDropper } from '@vueuse/core'
+
+const { isSupported, open, sRGBHex } = useEyeDropper()
+```
+
+## Component Usage
+
+```vue
+<template>
+  <UseEyeDropper v-slot="{ isSupported, sRGBHex, open }">
+    <button :disabled="!isSupported" @click="() => open()">
+      sRGBHex: {{ sRGBHex }}
+    </button>
+  </UseEyeDropper>
+</template>
+```
+
+## Type Declarations
+
+```ts
+export interface EyeDropperOpenOptions {
+  /**
+   * @see https://developer.mozilla.org/en-US/docs/Web/API/AbortSignal
+   */
+  signal?: AbortSignal
+}
+export interface EyeDropper {
+  new (): EyeDropper
+  open: (options?: EyeDropperOpenOptions) => Promise<{
+    sRGBHex: string
+  }>
+  [Symbol.toStringTag]: "EyeDropper"
+}
+export interface UseEyeDropperOptions {
+  /**
+   * Initial sRGBHex.
+   *
+   * @default ''
+   */
+  initialValue?: string
+}
+export interface UseEyeDropperReturn extends Supportable {
+  sRGBHex: ShallowRef<string>
+  open: (openOptions?: EyeDropperOpenOptions) => Promise<
+    | {
+        sRGBHex: string
+      }
+    | undefined
+  >
+}
+/**
+ * Reactive [EyeDropper API](https://developer.mozilla.org/en-US/docs/Web/API/EyeDropper_API)
+ *
+ * @see https://vueuse.org/useEyeDropper
+ *
+ * @__NO_SIDE_EFFECTS__
+ */
+export declare function useEyeDropper(
+  options?: UseEyeDropperOptions,
+): UseEyeDropperReturn
+```