Prepare Claude plugin for public review

[hopeatina]

Summary

• add MIT license metadata and root LICENSE for public marketplace review
• replace local-machine repo path in README with the public GitHub repository and license
• refresh the SDK lockfile entry to the MIT-licensed gateway SDK commit
• update next step wording to match Claude plugin directory submission

Verification

• npm run typecheck
• npm test
• npm run verify
• claude plugin validate .
• git diff --check

Notes

• The dependency lock now resolves @useorgx/orgx-gateway-sdk to useorgx/orgx-gateway-sdk@b32d034, where GitHub detects MIT.