feat: add new skills to skills-lock.json and update use-pixel-heat component

- Added new skills: find-skills, frontend-ui-engineering, and vercel-react-best-practices to skills-lock.json.
- Updated use-pixel-heat.ts to import both animate and AnimationPlaybackControls from motion for improved animation handling.

.agents/skills/vercel-react-best-practices/rules/advanced-init-once.md

@@ -0,0 +1,42 @@
+---
+title: Initialize App Once, Not Per Mount
+impact: LOW-MEDIUM
+impactDescription: avoids duplicate init in development
+tags: initialization, useEffect, app-startup, side-effects
+---
+
+## Initialize App Once, Not Per Mount
+
+Do not put app-wide initialization that must run once per app load inside `useEffect([])` of a component. Components can remount and effects will re-run. Use a module-level guard or top-level init in the entry module instead.
+
+**Incorrect (runs twice in dev, re-runs on remount):**
+
+```tsx
+function Comp() {
+  useEffect(() => {
+    loadFromStorage()
+    checkAuthToken()
+  }, [])
+
+  // ...
+}
+```
+
+**Correct (once per app load):**
+
+```tsx
+let didInit = false
+
+function Comp() {
+  useEffect(() => {
+    if (didInit) return
+    didInit = true
+    loadFromStorage()
+    checkAuthToken()
+  }, [])
+
+  // ...
+}
+```
+
+Reference: [Initializing the application](https://react.dev/learn/you-might-not-need-an-effect#initializing-the-application)