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/useAsyncValidator.md

@@ -0,0 +1,70 @@
+---
+category: '@Integrations'
+---
+
+# useAsyncValidator
+
+Wrapper for [`async-validator`](https://github.com/yiminghe/async-validator).
+
+## Install
+
+```bash
+npm i async-validator@^4
+```
+
+## Usage
+
+```ts
+import { useAsyncValidator } from '@vueuse/integrations/useAsyncValidator'
+```
+
+## Type Declarations
+
+```ts
+export type AsyncValidatorError = Error & {
+  errors: ValidateError[]
+  fields: Record<string, ValidateError[]>
+}
+export interface UseAsyncValidatorExecuteReturn {
+  pass: boolean
+  errors: AsyncValidatorError["errors"] | undefined
+  errorInfo: AsyncValidatorError | null
+  errorFields: AsyncValidatorError["fields"] | undefined
+}
+export interface UseAsyncValidatorReturn {
+  pass: ShallowRef<boolean>
+  isFinished: ShallowRef<boolean>
+  errors: ComputedRef<AsyncValidatorError["errors"] | undefined>
+  errorInfo: ShallowRef<AsyncValidatorError | null>
+  errorFields: ComputedRef<AsyncValidatorError["fields"] | undefined>
+  execute: () => Promise<UseAsyncValidatorExecuteReturn>
+}
+export interface UseAsyncValidatorOptions {
+  /**
+   * @see https://github.com/yiminghe/async-validator#options
+   */
+  validateOption?: ValidateOption
+  /**
+   * The validation will be triggered right away for the first time.
+   * Only works when `manual` is not set to true.
+   *
+   * @default true
+   */
+  immediate?: boolean
+  /**
+   * If set to true, the validation will not be triggered automatically.
+   */
+  manual?: boolean
+}
+/**
+ * Wrapper for async-validator.
+ *
+ * @see https://vueuse.org/useAsyncValidator
+ * @see https://github.com/yiminghe/async-validator
+ */
+export declare function useAsyncValidator(
+  value: MaybeRefOrGetter<Record<string, any>>,
+  rules: MaybeRefOrGetter<Rules>,
+  options?: UseAsyncValidatorOptions,
+): UseAsyncValidatorReturn & PromiseLike<UseAsyncValidatorReturn>
+```