Add Stripe MCP config to existing plugin

[ashwinm-oai]

Summary

• add Stripe MCP configuration pointing at the hosted Stripe MCP endpoint
• wire the existing Stripe plugin manifest to the bundled skills and MCP config
• keep the existing app-backed Stripe connector in place

Notes

• used the hosted Stripe MCP endpoint at https://mcp.stripe.com
• kept changes to plugin.json minimal: just skills and mcpServers

Validation

• validated plugins/stripe/.codex-plugin/plugin.json with jq
• validated plugins/stripe/.mcp.json with jq

[ashwinm-oai]

cleaned up to just be a skills change