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/get.md

@@ -0,0 +1,30 @@
+---
+category: Utilities
+---
+
+# get
+
+Shorthand for accessing `ref.value`
+
+## Usage
+
+```ts
+import { get } from '@vueuse/core'
+
+const a = ref(42)
+
+console.log(get(a)) // 42
+```
+
+## Type Declarations
+
+```ts
+/**
+ * Shorthand for accessing `ref.value`
+ */
+export declare function get<T>(ref: MaybeRef<T>): T
+export declare function get<T, K extends keyof T>(
+  ref: MaybeRef<T>,
+  key: K,
+): T[K]
+```