[codex] Add Google Search Console verification file

[CircleQMinh]

Summary

• add Google Search Console's HTML verification file to the shared public root
• remove the redundant SPA-only meta verification tag
• record Step 15 completion and Step 16 verification status in the SEO plan and handoff

Why

Production now deploys the React Router framework output. A file in public/ is copied unchanged into both SPA and framework build outputs, so Google can request the verification token from the canonical site root regardless of the selected deployment target.

Verification URL

https://www.dev-net-core.com/googlec6ac2a9be6ebed67.html

Expected response:

google-site-verification: googlec6ac2a9be6ebed67.html

Validation

• npm run lint
• npm run build
• npm run build:framework
• npm run finalize:framework
• npm run validate:framework
• confirmed the file exists with the expected text in public/, dist/, and build-framework/client/
• confirmed the framework preview returns 200 OK with the expected verification text