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/toRef.md

@@ -0,0 +1,75 @@
+---
+category: Reactivity
+alias: resolveRef
+---
+
+# toRef
+
+Normalize value/ref/getter to `ref` or `computed`.
+
+## Usage
+
+```ts
+import { toRef } from '@vueuse/core'
+
+const foo = ref('hi')
+
+const a = toRef(0) // Ref<number>
+const b = toRef(foo) // Ref<string>
+const c = toRef(() => 'hi') // ComputedRef<string>
+```
+
+## Differences from Vue's `toRef`
+
+VueUse's `toRef` is not the same as Vue’s `toRef` from the `vue` package.
+
+### VueUse `toRef`
+
+- Accepts **value**, **ref**, or **getter**
+- Returns:
+  - a **ref** for primitive values
+  - a **ref** for existing refs
+  - a **computed** for getter functions
+- Does **not** accept `object + key`
+- Getters always produce readonly computed values
+
+### Vue `toRef`
+
+- Accepts only:
+  - a **reactive object + property key**, or
+  - an existing **ref**
+- Produces a **writable ref** linked to the underlying reactive object
+- Does **not** accept primitive values
+- Does **not** accept getter functions
+
+### Summary
+
+| Behavior                 | VueUse `toRef`            | Vue `toRef`             |
+| ------------------------ | ------------------------- | ----------------------- |
+| Accepts primitive values | ✔️                        | ❌                      |
+| Accepts getter           | ✔️ (computed)             | ❌                      |
+| Accepts existing ref     | ✔️                        | ✔️                      |
+| Accepts object + key     | ❌                        | ✔️                      |
+| Writable                 | ✔️ (except getter)        | ✔️                      |
+| Purpose                  | Normalize to ref/computed | Bind to reactive object |
+
+## Type Declarations
+
+```ts
+/**
+ * Normalize value/ref/getter to `ref` or `computed`.
+ */
+export declare function toRef<T>(r: () => T): Readonly<Ref<T>>
+export declare function toRef<T>(r: ComputedRef<T>): ComputedRef<T>
+export declare function toRef<T>(r: MaybeRefOrGetter<T>): Ref<T>
+export declare function toRef<T>(r: T): Ref<T>
+export declare function toRef<T extends object, K extends keyof T>(
+  object: T,
+  key: K,
+): ToRef<T[K]>
+export declare function toRef<T extends object, K extends keyof T>(
+  object: T,
+  key: K,
+  defaultValue: T[K],
+): ToRef<Exclude<T[K], undefined>>
+```