docs: document full and embedded rendering with server authentication

README.md

@@ -4,8 +4,18 @@ ThothII is a human-reviewed NL-to-SQL workflow with a React frontend and a Fasti
 core. The portable deployment runs two application services plus the installation-local metadata
 catalog; DWH and LLM services remain external. Semantic services are bundled in Compose.
 
-Authentication is configured through the single host CLI tht: see the [local authentication guide](docs/install/authentication-local.md),
-[generic OIDC guide](docs/install/authentication-oidc.md), and [manual acceptance matrix](docs/testing/authentication-manual-acceptance.md).
+The same frontend supports **full** (its own header) and **embedded** (inside a
+portal). This choice is independent of authentication: the Mac uses full/local,
+Omics uses embedded/upstream with its existing login, and a standalone server
+can use full/OIDC. See [rendering architecture](docs/architecture/application-shell.md)
+and [configuration, Omics delivery and deploy](docs/operations/shell-and-localization.md).
+
+Local/OIDC authentication is configured through the host CLI `tht`; portal
+authentication is established by the trusted server proxy. See the
+[local guide](docs/install/authentication-local.md),
+[OIDC guide](docs/install/authentication-oidc.md),
+[upstream integration](docs/install/authentication-upstream.md), and
+[manual acceptance matrix](docs/testing/authentication-manual-acceptance.md).
 
 ## Docker Compose: local startup