refactor: remove dead boolean cell type and fix test name

Remove "b" from ExcelCell.t union and boolean from ExcelCell.v
since excelBoolean now returns string cells. Fix misleading test
name for undefined dynamicText case.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: samuelreichert

packages/pluggableWidgets/datagrid-web/src/features/data-export/__tests__/cell-readers.spec.ts

@@ -111,7 +111,7 @@ describe("cell-readers", () => {
             expect(cell.v).toBe("formatted text");
         });
 
-        it("exports n/a when unavailable", () => {
+        it("returns empty cell when dynamicText is undefined", () => {
             const col = column("Label", c => {
                 c.showContentAs = "dynamicText";
                 c.dynamicText = undefined;

packages/pluggableWidgets/datagrid-web/src/features/data-export/cell-readers.ts

@@ -4,10 +4,10 @@ import { ColumnsType, ShowContentAsEnum } from "../../../typings/DatagridProps";
 
 /** Represents a single Excel cell (SheetJS compatible) */
 export interface ExcelCell {
-    /** Cell type: 's' = string, 'n' = number, 'b' = boolean, 'd' = date */
-    t: "s" | "n" | "b" | "d";
+    /** Cell type: 's' = string, 'n' = number, 'd' = date */
+    t: "s" | "n" | "d";
     /** Underlying value */
-    v: string | number | boolean | Date;
+    v: string | number | Date;
     /** Optional Excel number/date format, e.g. "yyyy-mm-dd" or "$0.00" */
     z?: string;
     /** Optional pre-formatted display text */