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/toReactive.md

@@ -0,0 +1,41 @@
+---
+category: Reactivity
+---
+
+# toReactive
+
+Converts ref to reactive. Also made possible to create a "swapable" reactive object.
+
+## Usage
+
+```ts
+import { toReactive } from '@vueuse/core'
+import { ref } from 'vue'
+
+const refState = ref({ foo: 'bar' })
+
+console.log(refState.value.foo) // => 'bar'
+
+const state = toReactive(refState) // <--
+
+console.log(state.foo) // => 'bar'
+
+refState.value = { bar: 'foo' }
+
+console.log(state.foo) // => undefined
+console.log(state.bar) // => 'foo'
+```
+
+## Type Declarations
+
+```ts
+/**
+ * Converts ref to reactive.
+ *
+ * @see https://vueuse.org/toReactive
+ * @param objectRef A ref of object
+ */
+export declare function toReactive<T extends object>(
+  objectRef: MaybeRef<T>,
+): UnwrapNestedRefs<T>
+```