docs: reorganize operational documentation

docs/index.md

@@ -1,20 +1,29 @@
 # ThothII documentation
 
-ThothII is a human-in-the-loop datamart builder. It turns natural-language questions into validated SQL through an eight-phase workflow orchestrated by Pi.
+ThothII is a human-reviewed datamart builder. It turns a question into validated SQL through an
+eight-phase workflow: the model proposes; a reviewer makes the decisions that are persisted.
 
-The documentation is divided into two areas:
+Start with the path that matches the work you need to do:
 
-## ThothII technical documentation
+| I need to… | Start here |
+| --- | --- |
+| Install or operate one instance | [Install and first start](install/first-start.md) |
+| Add, update, or prepare a workspace | [Workspace operations](operations/workspaces.md) |
+| Ask a question and review the SQL workflow | [User guide](guida-utente.md) |
+| Configure and refresh an authoritative database catalog | [Database management](operations/database-management.md) |
+| Author and publish domain Evidence | [Evidence](evidence.md) |
+| Understand boundaries and persistence | [Architecture overview](architecture/overview.md) |
 
-This section explains the system architecture, workflow, operating contracts, Evidence, and Memory. Start with the [architecture overview](architecture/overview.md).
+## How the documentation is organised
 
-For local authentication, generic OIDC, and Authentik, see the [authentication documentation](architecture/authentication.md).
+- **Install and operate** documents host-side setup, authentication, lifecycle, workspaces, and
+  Pi administration.
+- **Use ThothII** documents the two application paths: reviewed NL→SQL sessions and administrative
+  database management.
+- **Architecture and contracts** explain why the system behaves as it does and define the
+  machine-facing boundaries. Consult them when integrating or changing an implementation; they
+  are not a substitute for an operator runbook.
 
-To install the application in Docker across the four operating contexts, using the env file,
-`compose.yaml`, the local/server overlay, and the mounted secret bundle, see [Docker installation in the four operating contexts](installazione-docker-4-contesti.md).
-
-For DWH REST with an installation-specific revocable key, see the [server guide](install/dwh-auth-server.md), [client enrollment guide](install/dwh-auth-client-enrollment.md), and [TLS guide](install/dwh-auth-tls.md). This component remains separate from the ThothII Compose stack.
-
-## General topics
-
-Operating and configuration notes that are not specific to the ThothII domain, such as how Pi resolves built-in, user-level, and project-level models. Start with [Pi model configuration](general/pi-configuration.md).
+The host-side `tht` command is the operator interface. The Python `tht` inside `harness/` is a
+different, internal workflow CLI invoked by the core. In examples, use an absolute installation
+descriptor path whenever discovery is not unambiguous.