feat: marketplace submission guide + automation for all AI tool stores

[varkart]

Track submission of visualcave to each AI tool marketplace.

Marketplaces

Claude Code Skills Store

• Plugin config: .claude-plugin/plugin.json ✅
• Marketplace config: .claude-plugin/marketplace.json ✅
• Submission: Manual — submit to Anthropic skills directory (no public self-service yet as of mid-2026)
• Action needed: Monitor https://claude.ai/marketplace for self-service submissions

OpenAI GPT Store / Codex Plugins

• Plugin config: .codex-plugin/plugin.json ✅
• Submission: Via OpenAI developer portal — https://platform.openai.com/plugins
• Action needed: Register OAuth, create plugin manifest at /.well-known/ai-plugin.json

Google Gemini Extensions

• Extension config: gemini-extension.json ✅
• Submission: Via Google AI Studio or Gemini for Workspace marketplace
• Action needed: Review Google Extensions policy, test with Gemini CLI locally first

Cursor Extension Marketplace

• Rules file: .cursor/rules/visualcave.mdc ✅
• Submission: Cursor does not have a public skill/rules marketplace (as of 2026) — distribution is via GitHub clone
• Action needed: Monitor Cursor changelog for marketplace launch

Kiro (Amazon)

• .kiro/rules/ support: ❌ not yet added — see issue feat: Kiro CLI support (.kiro/rules) #7
• Submission: No public marketplace yet

Automation ideas

• GH Action that validates plugin.json on each release
• Script to bump version in all plugin manifests simultaneously