Add Socket.IO collaborative draw board template

[kenproxx]

Summary

• add a Socket.IO collaborative draw board template for Codesphere
• include real-time room-based drawing, shared clear-board events, online presence, and JPG export
• add Codesphere ci.yml, metadata, and setup/deployment README

Verification

• npm.cmd install
• npm.cmd run check
• npm.cmd audit --audit-level=moderate
• smoke test: home page returned 200 and /socket.io/socket.io.js returned 200 on local server
• git diff --check

Closes #8