Add Gemini extension (clipboard-first flow) to contrib

[GravityPoet]

Summary

Adds a new community extension under contrib/Gemini.popclipext.

The extension:

• prompts for a question after text selection,
• builds a structured prompt with selected text + question,
• copies the prompt to clipboard,
• opens https://gemini.google.com/app in Chrome for paste-and-send.

Why clipboard-first

Gemini web auto-submit is inconsistent across browser automation settings and accounts. This extension uses a stable flow that works with minimal setup.

Included files

• Config.json
• gemini.applescript
• gemini.png
• Readme.md (usage + changelog + credits)

Manual test

• Installed extension locally in PopClip on macOS
• Verified prompt dialog, clipboard output, and Gemini tab opening behavior

[GravityPoet]

Already updated to the latest version

[GravityPoet]

Hi maintainer, friendly ping for review when you have time. I have validated the extension behavior locally and can update promptly if any changes are required. Thank you!