feat(mcp): add Cloudflare Worker transport

[bunizao]

Summary

• add a stateless Streamable HTTP MCP Worker behind Cloudflare Access Managed OAuth
• verify Access JWT assertions and isolate the fixed Ed API credential
• add workerd integration tests, Wrangler tooling, CI checks, and deployment documentation

Verification

• npm run check
• npm run test:node
• npm run test:worker
• npm run test:remote
• npm run worker:types:check
• npm run build
• npm run pack:check
• npm run pack:smoke
• npm run skill:generate && git diff --exit-code SKILL.md

Notes

• no Worker deployment or Cloudflare account changes are included
• writes remain disabled by default via MCP_WRITE_ENABLED=false
• the existing stdio and Bun remote adapters remain available

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[bunizao]

Closed because this branch was pushed to the wrong repository. The corrected PR is bunizao/edstem-cli#2.