docs: document ChatGPT MCP OAuth

CHATGPT-SETUP.md

@@ -14,13 +14,25 @@ app inside another person’s ChatGPT account and never stores OAuth tokens.
 4. Start a new chat or refresh the app connection.
 5. Test with: `Покажи активные проекты с датой завершения и статусом.`
 
+The server publishes OAuth 2.1 discovery for the root resource and supports
+ChatGPT Client ID Metadata Documents (CIMD), PKCE S256 and the
+`private_key_jwt` token-endpoint authentication method. Keep the app URL as
+`https://shd.xyz.su/mcp`; the retired `/mcp/system-data` resource is not a
+valid replacement for the root MCP resource.
+
 The expected flow is:
 
 1. ChatGPT calls `shd_list_projects` with `archived: false`.
-2. ChatGPT may call `shd_render_projects_widget` with the returned project
-   array.
-3. The widget renders the sorted register and can call `shd_get_project` for
-   a selected row.
+2. ChatGPT may call a module render tool after the corresponding list tool:
+   `shd_render_projects_widget`, `shd_render_documents_widget`,
+   `shd_render_tasks_widget`, `shd_render_finance_widget` or
+   `shd_render_crm_widget`.
+3. The selected widget renders a read-only register and can call the matching
+   detail tool for one selected row.
+
+The widget resources are versioned at `ui://shd/active-projects/v1.html`,
+`ui://shd/documents/v1.html`, `ui://shd/tasks/v1.html`,
+`ui://shd/finance/v1.html` and `ui://shd/crm/v1.html`.
 
 The MCP tools remain usable without the widget. A failed OAuth connection is
 an account/endpoint configuration problem, not a missing token in this repo.