docs: add Low-Code formula navigation

docs/en/docs-nav.json

@@ -2153,6 +2153,14 @@
           "text": "Low-Code Designer",
           "path": "low-code/designer.md"
         },
+        {
+          "text": "Calculated and Rollup Properties",
+          "path": "low-code/formula-properties.md"
+        },
+        {
+          "text": "Low-Code Expression Language",
+          "path": "low-code/expression-language.md"
+        },
         {
           "text": "React Runtime",
           "path": "low-code/react-runtime.md"

docs/en/low-code/designer.md

@@ -42,6 +42,8 @@ Use **Data** to define the domain model.
 
 Entities contain properties, display names, display property configuration, inherited audit fields, relations, and optional interceptors. Enums are created once and then used by enum properties.
 
+For virtual fields derived from the current record or related records, see [Calculated and Rollup Properties](formula-properties.md). For the supported scalar formula syntax, see the [Low-Code Expression Language](expression-language.md) reference.
+
 ![Entity summary in the designer](images/designer-entity.png)
 
 ![Entity property list](images/designer-properties.png)

docs/en/low-code/index.md

@@ -176,6 +176,8 @@ The designer stores and reads the same descriptor metadata described in the refe
 | Topic | Use it for |
 |-------|------------|
 | [Designer](designer.md) | Admin Console tabs, entity/page/form setup, permissions, and health |
+| [Calculated and Rollup Properties](formula-properties.md) | Virtual scalar formulas and related-record aggregates authored in the Designer |
+| [Low-Code Expression Language](expression-language.md) | Provider-safe scalar syntax used by calculated properties and formula backfills |
 | [Add Low-Code to an Existing Solution](add-to-existing-solution.md) | Retrofitting an existing EF Core solution with Studio import plus manual backend and React wiring |
 | [Use Low-Code from a Non-React Application](non-react-ui-integration.md) | Keeping an MVC, Razor Pages, Angular, or Blazor UI while hosting the React Low-Code runtime and Designer alongside it |
 | [React Runtime](react-runtime.md) | React package wiring, routes, menu items, filters, forms, and export |
@@ -207,6 +209,8 @@ The generated pages are powered by these services:
 ## See Also
 
 * [Low-Code Designer](designer.md)
+* [Calculated and Rollup Properties](formula-properties.md)
+* [Low-Code Expression Language](expression-language.md)
 * [Add Low-Code to an Existing Solution](add-to-existing-solution.md)
 * [Use Low-Code from a Non-React Application](non-react-ui-integration.md)
 * [React Runtime](react-runtime.md)

docs/en/low-code/model-json.md

@@ -241,6 +241,8 @@ Entities describe the persisted data model. UI is not configured with legacy pro
 | `foreignKey` | Lookup relation metadata |
 | `validators` | Backend/UI validation rules |
 
+For virtual calculated fields and related-record aggregates, see [Calculated and Rollup Properties](formula-properties.md). The [Low-Code Expression Language](expression-language.md) reference documents the scalar syntax used by calculated properties and formula backfills.
+
 ### Property Types
 
 | Type | Description |