Add badges to README for project visibility

Added badges for GitHub stars, license, and PRs.

README.md

@@ -1,3 +1,7 @@
+![GitHub stars](https://img.shields.io/github/stars/phuryn/pm-skills)
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow?style=flat-square)](https://github.com/phuryn/pm-skills/blob/main/LICENSE)
+[![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen?style=flat-square)](https://github.com/phuryn/pm-skills/blob/main/CONTRIBUTING.md)
+
 # PM Skills Marketplace: The AI Operating System for Better Product Decisions
 
 > 65 PM skills and 36 chained workflows across 8 plugins. Claude Code, Cowork, and more. From discovery to strategy, execution, launch, and growth.