feat: add 4 universal skills from cli-ai-skills

- Add audio-transcriber skill (v1.2.0): Transform audio to Markdown with Whisper
- Add youtube-summarizer skill (v1.2.0): Generate summaries from YouTube videos
- Update prompt-engineer skill: Enhanced with 11 optimization frameworks
- Update skill-creator skill: Improved automation workflow

All skills are zero-config, cross-platform (Claude Code, Copilot CLI, Codex)
and follow Quality Bar V4 standards.

Source: https://github.com/ericgandrade/cli-ai-skills

README.md

@@ -1,6 +1,6 @@
-# 🌌 Antigravity Awesome Skills: 631+ Agentic Skills for Claude Code, Gemini CLI, Cursor, Copilot & More
+# 🌌 Antigravity Awesome Skills: 633+ Agentic Skills for Claude Code, Gemini CLI, Cursor, Copilot & More
 
-> **The Ultimate Collection of 631+ Universal Agentic Skills for AI Coding Assistants — Claude Code, Gemini CLI, Codex CLI, Antigravity IDE, GitHub Copilot, Cursor, OpenCode, AdaL**
+> **The Ultimate Collection of 633+ Universal Agentic Skills for AI Coding Assistants — Claude Code, Gemini CLI, Codex CLI, Antigravity IDE, GitHub Copilot, Cursor, OpenCode, AdaL**
 
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 [![Claude Code](https://img.shields.io/badge/Claude%20Code-Anthropic-purple)](https://claude.ai)
@@ -13,7 +13,7 @@
 [![AdaL CLI](https://img.shields.io/badge/AdaL%20CLI-SylphAI-pink)](https://sylph.ai/)
 [![ASK Supported](https://img.shields.io/badge/ASK-Supported-blue)](https://github.com/yeasy/ask)
 
-**Antigravity Awesome Skills** is a curated, battle-tested library of **631 high-performance agentic skills** designed to work seamlessly across all major AI coding assistants:
+**Antigravity Awesome Skills** is a curated, battle-tested library of **633 high-performance agentic skills** designed to work seamlessly across all major AI coding assistants:
 
 - 🟣 **Claude Code** (Anthropic CLI)
 - 🔵 **Gemini CLI** (Google DeepMind)
@@ -32,7 +32,7 @@ This repository provides essential skills to transform your AI assistant into a
 - [🔌 Compatibility & Invocation](#compatibility--invocation)
 - [📦 Features & Categories](#features--categories)
 - [🎁 Curated Collections (Bundles)](#curated-collections)
-- [📚 Browse 631+ Skills](#browse-631-skills)
+- [📚 Browse 633+ Skills](#browse-633-skills)
 - [🛠️ Installation](#installation)
 - [🤝 How to Contribute](#how-to-contribute)
 - [👥 Contributors & Credits](#credits--sources)
@@ -132,7 +132,7 @@ The repository is organized into specialized domains to transform your AI into a
 
 [Check out our Starter Packs in docs/BUNDLES.md](docs/BUNDLES.md) to find the perfect toolkit for your role.
 
-## Browse 631+ Skills
+## Browse 633+ Skills
 
 We have moved the full skill registry to a dedicated catalog to keep this README clean.