Fix icon build process and README

- Update gulpfile to copy PNG files to dist
- Remove broken image link from README
- Rebuild with PNG icon included

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

README.md

@@ -1,7 +1,5 @@
 # n8n-nodes-strike
 
-![Strike Logo](https://strike.me/assets/images/logo.png)
-
 This is an n8n community node for integrating with the [Strike API](https://strike.me), enabling Bitcoin and Lightning Network payment operations within your n8n workflows.
 
 ## ⚠️ Important Disclaimer