feat: add ADvx persona frontend

[layla-aa]

What changed

• add the complete ADvx persona web frontend under frontend/
• include all local visual assets, chat view, XYZ persona editor, tests, and build scripts
• keep generated output and dependencies out of version control

Why

The hackathon repository already contains hardware and SDK projects, so the frontend is isolated in its own subdirectory instead of replacing existing code.

Validation

• npm ci
• npm test — 45 passing
• npm run build