feat: add remotion-best-practices skill from remotion-dev/skills

Imported official Remotion skill for video creation in React:
- 28 modular rule files covering animations, audio, video, captions, 3D, etc.
- Added author (remotion-dev) and version (1.0) metadata
- Updated skill count: 224 → 225
- Regenerated skills_index.json

Source: https://github.com/remotion-dev/skills

skills/remotion-best-practices/rules/text-animations.md

@@ -0,0 +1,20 @@
+---
+name: text-animations
+description: Typography and text animation patterns for Remotion.
+metadata:
+  tags: typography, text, typewriter, highlighter ken
+---
+
+## Text animations
+
+Based on `useCurrentFrame()`, reduce the string character by character to create a typewriter effect.
+
+## Typewriter Effect
+
+See [Typewriter](assets/text-animations-typewriter.tsx) for an advanced example with a blinking cursor and a pause after the first sentence.
+
+Always use string slicing for typewriter effects. Never use per-character opacity.
+
+## Word Highlighting
+
+See [Word Highlight](assets/text-animations-word-highlight.tsx) for an example for how a word highlight is animated, like with a highlighter pen.