Scaffold web React UI shell for traverse-starter

[enricopiovesan]

Purpose

Set up the initial React app shell at apps/traverse-starter/web-react with no Traverse business logic, configured for local runtime connection.

Definition of Done

• apps/traverse-starter/web-react exists
• UI shell starts locally
• Contains no Traverse business logic
• Has configuration for local Traverse runtime URL/discovery
• Documents pinned Traverse release and TRAVERSE_REPO override behavior

Notes

TRAVERSE_REPO=/path/to/Traverse override is for active framework development only. The canonical path uses a pinned released Traverse runtime/CLI.