Scaffold youaskm3 web React UI shell

[enricopiovesan]

Summary

• Adds apps/youaskm3/web-react with React 18 + TypeScript + Vite + Vitest + ESLint
• Mirrors the traverse-starter toolchain exactly (same deps, same tsconfig, same ESLint config)
• No Traverse business logic — shell only renders runtime-provided data
• Registers the new workspace in the root package.json

Closes #11

Definition of Done

• apps/youaskm3/web-react exists with React 18 + TypeScript + Vite + Vitest + ESLint
• npm run dev starts the app locally
• npm run typecheck and npm run lint pass clean
• No Traverse business logic present
• README documents local setup and TRAVERSE_REPO override

Validation

npm run typecheck -w apps/youaskm3/web-react  # pass
npm run lint -w apps/youaskm3/web-react        # pass
npm run test -w apps/youaskm3/web-react        # 2 tests pass