Built-in Claude provider now uses the CLIProxy root URL instead of /api/provider/claude (which 404'd since base CLIProxy registers /v1/messages at root). Repairs stale local Claude settings, keeps non-Claude providers on their scoped routes, and applies the same root-URL rule to the ccs api create --cliproxy-provider claude bridge path via a shared buildCliproxyProviderPath helper. Closes#1545.