Prepare and publish SPARQLPrompt to Chrome Web Store

[twhetzel]

Description:
Complete the process of publishing the extension to the Chrome Web Store:

• Create developer account ($5 one-time fee)
• Prepare store listing (screenshots, descriptions, promotional images)
• Package extension for store submission
• Submit for review
• Handle any review feedback
• Maintain store listing after publication

Acceptance Criteria:

• Extension published on Chrome Web Store
• Store listing complete with all required assets
• Extension passes Chrome Web Store review
• Update mechanism works for store version
• Store listing maintained and updated