Cache page and settings are enabled by default on self-hosted Tuist servers

On self-hosted Tuist servers, the Cache page, sidebar entry, Usage page, and account settings section are now available by default. Previously, these surfaces were gated behind the :kura feature flag, so operators had to visit /ops/flags to enable them before they could generate control-plane credentials. The deployment already grants the self-hosted-cache entitlement unconditionally, so that step was unnecessary friction. The managed cache-server provisioning UI is now hidden when it does not apply, so self-hosters see only credential generation and registered nodes. The self-hosting docs were also corrected to reflect the actual TUIST_CACHE_ENDPOINTS routing, the fact that registration is dashboard-only on self-hosted, and that single-node setups use http:// KURA_NODE_URL without peer m.