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/useCeil.md

@@ -0,0 +1,31 @@
+---
+category: '@Math'
+---
+
+# useCeil
+
+Reactive `Math.ceil`
+
+## Usage
+
+```ts
+import { useCeil } from '@vueuse/math'
+
+const value = ref(0.95)
+const result = useCeil(value) // 1
+```
+
+## Type Declarations
+
+```ts
+/**
+ * Reactive `Math.ceil`.
+ *
+ * @see https://vueuse.org/useCeil
+ *
+ * @__NO_SIDE_EFFECTS__
+ */
+export declare function useCeil(
+  value: MaybeRefOrGetter<number>,
+): ComputedRef<number>
+```