Add searchable tags and categories to plugin manifests for better discoverability

[saismrutiranjan18]

The current plugin.json structure doesn't include:

• Searchable tags/keywords for plugin discovery
• Categories for organizing plugins (e.g., "productivity", "data-analysis", "communication")
• Difficulty level (beginner, intermediate, advanced)
• Required vs optional MCP connectors
• Use case examples

[Albab-Hasan]

I solved this in my latest commit. check it out. you might want to fork my repo, because none of the pr's are getting through