docs(centralui): template picker on Create Instance, New Instance… from the Templates tree

Claude-Session: https://claude.ai/code/session_01G2GHPnbbKGvyyfbr2XBRVH

docs/plans/2026-08-21-create-instance-bindings-design.md

@@ -42,8 +42,12 @@ Same `FlattenSession` memo, so it is one template-chain walk per call.
 
 ### 3.2 Create page (CentralUI `InstanceCreate.razor` + new code-behind)
 
+- **Superseded 2026-08-21 (`docs/plans/2026-08-21-template-picker.md`):** the Template `<select>`
+  described below is now a read-only folder-path field + `TemplatePickerDialog`, and the page takes
+  a `?templateId=` query preselect (what the Templates tree's "New Instance…" navigates with). The
+  card's trigger is unchanged — a pick still calls `OnTemplateOrSiteChangedAsync()`.
 - The **Connection Bindings** card appears once Template *and* Site are set; changing either
-  re-runs the preview (debounced by the select's change event — no typing involved) and resets
+  re-runs the preview (a pick or a site-select change — no typing involved) and resets
   the card. Rows = `PreviewAsync(...).Attributes.Where(DefaultDataSourceReference ?? DataSourceReference != null)`
   → `BindingRow(canonicalName, default, null, null)` → `BindingGroupBuilder.Build(rows, siteConnectionIds)`.
 - **Group rows** are the Configure page's group-header row (connection select, Object input,