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/useRafFn.md

@@ -0,0 +1,68 @@
+---
+category: Animation
+---
+
+# useRafFn
+
+Call function on every `requestAnimationFrame`. With controls of pausing and resuming.
+
+## Usage
+
+```ts
+import { useRafFn } from '@vueuse/core'
+import { shallowRef } from 'vue'
+
+const count = shallowRef(0)
+
+const { pause, resume } = useRafFn(() => {
+  count.value++
+  console.log(count.value)
+})
+```
+
+## Type Declarations
+
+```ts
+export interface UseRafFnCallbackArguments {
+  /**
+   * Time elapsed between this and the last frame.
+   */
+  delta: number
+  /**
+   * Time elapsed since the creation of the web page. See {@link https://developer.mozilla.org/en-US/docs/Web/API/DOMHighResTimeStamp#the_time_origin Time origin}.
+   */
+  timestamp: DOMHighResTimeStamp
+}
+export interface UseRafFnOptions extends ConfigurableWindow {
+  /**
+   * Start the requestAnimationFrame loop immediately on creation
+   *
+   * @default true
+   */
+  immediate?: boolean
+  /**
+   * The maximum frame per second to execute the function.
+   * Set to `null` to disable the limit.
+   *
+   * @default null
+   */
+  fpsLimit?: MaybeRefOrGetter<number | null>
+  /**
+   * After the requestAnimationFrame loop executed once, it will be automatically stopped.
+   *
+   * @default false
+   */
+  once?: boolean
+}
+/**
+ * Call function on every `requestAnimationFrame`. With controls of pausing and resuming.
+ *
+ * @see https://vueuse.org/useRafFn
+ * @param fn
+ * @param options
+ */
+export declare function useRafFn(
+  fn: (args: UseRafFnCallbackArguments) => void,
+  options?: UseRafFnOptions,
+): Pausable
+```