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/useNProgress.md

@@ -0,0 +1,78 @@
+---
+category: '@Integrations'
+---
+
+# useNProgress
+
+Reactive wrapper for [`nprogress`](https://github.com/rstacruz/nprogress).
+
+## Install
+
+```bash
+npm i nprogress@^0
+```
+
+## Usage
+
+```ts {6}
+import { useNProgress } from '@vueuse/integrations/useNProgress'
+
+const { isLoading } = useNProgress()
+
+function toggle() {
+  isLoading.value = !isLoading.value
+}
+```
+
+### Passing a progress percentage
+
+You can pass a percentage to indicate where the bar should start from.
+
+```ts {3}
+import { useNProgress } from '@vueuse/integrations/useNProgress'
+
+const { progress } = useNProgress(0.5)
+
+function done() {
+  progress.value = 1.0
+}
+```
+
+> To change the progress percentage, set `progress.value = n`, where n is a number between 0..1.
+
+### Customization
+
+Just edit [nprogress.css](https://github.com/rstacruz/nprogress/blob/master/nprogress.css) to your liking. Tip: you probably only want to find and replace occurrences of #29d.
+
+You can [configure](https://github.com/rstacruz/nprogress#configuration) it by passing an object as a second parameter.
+
+```ts {4}
+import { useNProgress } from '@vueuse/integrations/useNProgress'
+
+useNProgress(null, {
+  minimum: 0.1,
+  // ...
+})
+```
+
+## Type Declarations
+
+```ts
+export type UseNProgressOptions = Partial<NProgressOptions>
+export interface UseNProgressReturn {
+  isLoading: WritableComputedRef<boolean, boolean>
+  progress: Ref<number | null | undefined>
+  start: () => NProgress
+  done: (force?: boolean) => NProgress
+  remove: () => void
+}
+/**
+ * Reactive progress bar.
+ *
+ * @see https://vueuse.org/useNProgress
+ */
+export declare function useNProgress(
+  currentProgress?: MaybeRefOrGetter<number | null | undefined>,
+  options?: UseNProgressOptions,
+): UseNProgressReturn
+```