feat: Import 35+ skills, merge duplicates, add openclaw installer

Major updates:
- Added 35+ new skills from awesome-opencode-skills and antigravity repos
- Merged SEO skills into seo-master
- Merged architecture skills into architecture
- Merged security skills into security-auditor and security-coder
- Merged testing skills into testing-master and testing-patterns
- Merged pentesting skills into pentesting
- Renamed website-creator to thai-frontend-dev
- Replaced skill-creator with github version
- Removed Chutes references (use MiniMax API instead)
- Added install-openclaw-skills.sh for cross-platform installation
- Updated .env.example with MiniMax API credentials

skills/video-downloader/SKILL.md

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+---
+name: video-downloader
+description: Downloads videos from YouTube and other platforms for offline viewing, editing, or archival. Handles various formats and quality options.
+---
+
+# Video Downloader
+
+This skill downloads videos from YouTube and other platforms directly to your computer.
+
+## Prerequisites
+
+- **Python 3.7+**: Required for video download scripts
+- **yt-dlp or yt-dlp**: Video download utility (install via pip)
+- **FFmpeg**: For video format conversion (optional but recommended)
+
+## When to Use This Skill
+
+- Downloading YouTube videos for offline viewing
+- Saving educational content for reference
+- Archiving important videos
+- Getting video files for editing or repurposing
+- Downloading your own content from platforms
+- Saving conference talks or webinars
+
+## What This Skill Does
+
+1. **Downloads Videos**: Fetches videos from YouTube and other platforms
+2. **Quality Selection**: Lets you choose resolution (480p, 720p, 1080p, 4K)
+3. **Format Options**: Downloads in various formats (MP4, WebM, audio-only)
+4. **Batch Downloads**: Can download multiple videos or playlists
+5. **Metadata Preservation**: Saves title, description, and thumbnail
+
+## How to Use
+
+### Basic Download
+
+```
+Download this YouTube video: https://youtube.com/watch?v=...
+```
+
+```
+Download this video in 1080p quality
+```
+
+### Audio Only
+
+```
+Download the audio from this YouTube video as MP3
+```
+
+### Playlist Download
+
+```
+Download all videos from this YouTube playlist: [URL]
+```
+
+### Batch Download
+
+```
+Download these 5 YouTube videos:
+1. [URL]
+2. [URL]
+...
+```
+
+## Example
+
+**User**: "Download this YouTube video: https://youtube.com/watch?v=abc123"
+
+**Output**:
+```
+Downloading from YouTube...
+
+Video: "How to Build Products Users Love"
+Channel: Lenny's Podcast
+Duration: 45:32
+Quality: 1080p
+
+Progress: ████████████████████ 100%
+
+✓ Downloaded: how-to-build-products-users-love.mp4
+✓ Saved thumbnail: how-to-build-products-users-love.jpg
+✓ Size: 342 MB
+
+Saved to: ~/Downloads/
+```
+
+**Inspired by:** Lenny's workflow from his newsletter
+
+## Important Notes
+
+⚠️ **Copyright & Fair Use**
+- Only download videos you have permission to download
+- Respect copyright laws and platform terms of service
+- Use for personal, educational, or fair use purposes
+- Don't redistribute copyrighted content
+
+## Tips
+
+- Specify quality if you need lower file size (720p vs 1080p)
+- Use audio-only for podcasts or music to save space
+- Download to a dedicated folder to stay organized
+- Check file size before downloading on slow connections
+
+## Common Use Cases
+
+- **Education**: Save tutorials and courses for offline learning
+- **Research**: Archive videos for reference
+- **Content Creation**: Download your own content from platforms
+- **Backup**: Save important videos before they're removed
+- **Offline Viewing**: Watch videos without internet access
+