feat: Complete fleet — 94 skills across 10+ domains

Pulled ALL skills from 15 source repositories:
- anthropics/skills: 16 (docs, design, MCP, testing)
- obra/superpowers: 14 (TDD, debugging, agents, planning)
- coreyhaines31/marketingskills: 25 (marketing, CRO, SEO, growth)
- better-auth/skills: 5 (auth patterns)
- vercel-labs/agent-skills: 5 (React, design, Vercel)
- antfu/skills: 16 (Vue, Vite, Vitest, pnpm, Turborepo)
- Plus 13 individual skills from various repos

Mosaic Stack is not limited to coding — the Orchestrator and
subagents serve coding, business, design, marketing, writing,
logistics, analysis, and more.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

skills/vueuse-functions/references/useIntersectionObserver.md

@@ -0,0 +1,118 @@
+---
+category: Elements
+---
+
+# useIntersectionObserver
+
+Detects that a target element's visibility.
+
+## Usage
+
+```vue
+<script setup lang="ts">
+import { useIntersectionObserver } from '@vueuse/core'
+import { shallowRef, useTemplateRef } from 'vue'
+
+const target = useTemplateRef('target')
+const targetIsVisible = shallowRef(false)
+
+const { stop } = useIntersectionObserver(
+  target,
+  ([entry], observerElement) => {
+    targetIsVisible.value = entry?.isIntersecting || false
+  },
+)
+</script>
+
+<template>
+  <div ref="target">
+    <h1>Hello world</h1>
+  </div>
+</template>
+```
+
+## Directive Usage
+
+```vue
+<script setup lang="ts">
+import { vIntersectionObserver } from '@vueuse/components'
+import { shallowRef, useTemplateRef } from 'vue'
+
+const root = useTemplateRef('root')
+
+const isVisible = shallowRef(false)
+
+function onIntersectionObserver([entry]: IntersectionObserverEntry[]) {
+  isVisible.value = entry?.isIntersecting || false
+}
+</script>
+
+<template>
+  <div>
+    <p>
+      Scroll me down!
+    </p>
+    <div v-intersection-observer="onIntersectionObserver">
+      <p>Hello world!</p>
+    </div>
+  </div>
+
+  <!-- with options -->
+  <div ref="root">
+    <p>
+      Scroll me down!
+    </p>
+    <div v-intersection-observer="[onIntersectionObserver, { root }]">
+      <p>Hello world!</p>
+    </div>
+  </div>
+</template>
+```
+
+[IntersectionObserver MDN](https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver/IntersectionObserver)
+
+## Type Declarations
+
+```ts
+export interface UseIntersectionObserverOptions extends ConfigurableWindow {
+  /**
+   * Start the IntersectionObserver immediately on creation
+   *
+   * @default true
+   */
+  immediate?: boolean
+  /**
+   * The Element or Document whose bounds are used as the bounding box when testing for intersection.
+   */
+  root?: MaybeComputedElementRef | Document
+  /**
+   * A string which specifies a set of offsets to add to the root's bounding_box when calculating intersections.
+   */
+  rootMargin?: string
+  /**
+   * Either a single number or an array of numbers between 0.0 and 1.
+   * @default 0
+   */
+  threshold?: number | number[]
+}
+export interface UseIntersectionObserverReturn extends Pausable {
+  isSupported: ComputedRef<boolean>
+  stop: () => void
+}
+/**
+ * Detects that a target element's visibility.
+ *
+ * @see https://vueuse.org/useIntersectionObserver
+ * @param target
+ * @param callback
+ * @param options
+ */
+export declare function useIntersectionObserver(
+  target:
+    | MaybeComputedElementRef
+    | MaybeRefOrGetter<MaybeElement[]>
+    | MaybeComputedElementRef[],
+  callback: IntersectionObserverCallback,
+  options?: UseIntersectionObserverOptions,
+): UseIntersectionObserverReturn
+```