fix: trim leading/trailing whitespace from Excel header cells on upload

Header matching in searchDataInExcel() was case-insensitive but not
whitespace-tolerant, so a header like " SOME_CHAR" (an easy defect to
pick up via copy-paste from another spreadsheet/system) was reported as
a missing column and aborted the whole upload.

- trim() the cell value before matching, alongside the existing
  toLowerCase() normalization
- add spreadsheet-util.spec.ts (no prior spec file existed) covering
  the trimmed match and a regression guard that a genuinely different
  header is still correctly reported missing
- add a Cypress case + fixture in excel.cy.ts covering the same defect
  end to end

client/cypress/e2e/excel.cy.ts

@@ -386,6 +386,19 @@ context('excel tests: ', function () {
       })
   })
 
+  it('24 | Uploads Excel with leading whitespace in header row (should still succeed)', (done) => {
+    openTableFromTree(libraryToOpenIncludes, 'mpe_x_test')
+
+    // Every header except the first has a leading space, matching a
+    // real-world defect from copy-pasting between spreadsheets/systems.
+    // Header matching must tolerate
+    // this rather than reporting the columns missing and aborting.
+    attachExcelFile('leading_whitespace_header_excel.xlsx', () => {
+      submitExcel()
+      rejectExcel(done)
+    })
+  })
+
   // Large files break Cypress
 
   // it ('? | Uploads Excel with size of 5MB', (done) => {

client/src/app/shared/spreadsheet-util/spreadsheet-util.spec.ts

@@ -0,0 +1,78 @@
+import { BehaviorSubject } from 'rxjs'
+import * as XLSX from '@sheet/crypto'
+import { SpreadsheetUtil } from './spreadsheet-util'
+import { LicenceState } from 'src/app/models/LicenceState'
+import { ParseParams } from 'src/app/models/ParseParams.interface'
+import { SearchDataExcelResult } from 'src/app/models/SearchDataExcelResult.interface'
+
+describe('SpreadsheetUtil - header matching', () => {
+  // licenceState is unused by searchDataInExcel, so an empty stub is fine.
+  const buildSpreadsheetUtil = () =>
+    new SpreadsheetUtil({
+      licenceState: new BehaviorSubject<LicenceState>({} as LicenceState)
+    })
+
+  const buildWorkbook = (headerRow: string[], dataRow: any[]) => {
+    const ws = XLSX.utils.aoa_to_sheet([headerRow, dataRow])
+    const wb = XLSX.utils.book_new()
+
+    XLSX.utils.book_append_sheet(wb, ws, 'Sheet1')
+
+    return wb
+  }
+
+  // searchDataInExcel only reads headerArray/headerPks off ParseParams; the
+  // other required fields (dcValidator, etc.) are irrelevant here, so a
+  // minimal cast object stands in for a full ParseParams.
+  const buildParseParams = (): ParseParams =>
+    ({
+      headerArray: ['PRIMARY_KEY_FIELD', 'SOME_CHAR', 'SOME_NUM'],
+      headerPks: ['PRIMARY_KEY_FIELD']
+    }) as any as ParseParams
+
+  // searchDataInExcel is private; there's no existing precedent in this
+  // codebase for testing private methods, so this casts through `any` to
+  // reach it directly rather than exercising it via the public
+  // parseSpreadsheetFile (which would need a real File/FileReader).
+  const searchDataInExcel = (
+    spreadsheetUtil: SpreadsheetUtil,
+    wb: XLSX.WorkBook,
+    parseParams: ParseParams
+  ): SearchDataExcelResult =>
+    (spreadsheetUtil as any).searchDataInExcel(wb, parseParams)
+
+  it('matches headers with leading whitespace against the expected clean header names', () => {
+    const wb = buildWorkbook(
+      ['PRIMARY_KEY_FIELD', ' SOME_CHAR', ' SOME_NUM'],
+      [1, 'a value', 42]
+    )
+
+    const result = searchDataInExcel(
+      buildSpreadsheetUtil(),
+      wb,
+      buildParseParams()
+    )
+
+    expect(result.missing).toBeUndefined()
+    expect(result.found).toBeDefined()
+    expect(result.found?.headers).toContain('some_char')
+    expect(result.found?.headers).toContain('some_num')
+  })
+
+  it('still reports a genuinely different header as missing (no over-broadening)', () => {
+    const wb = buildWorkbook(
+      ['PRIMARY_KEY_FIELD', ' SOME_CHARX', ' SOME_NUM'],
+      [1, 'a value', 42]
+    )
+
+    const result = searchDataInExcel(
+      buildSpreadsheetUtil(),
+      wb,
+      buildParseParams()
+    )
+
+    expect(result.found).toBeUndefined()
+    expect(result.missing).toBeDefined()
+    expect(result.missing?.[0].missingHeaders).toContain('SOME_CHAR')
+  })
+})

client/src/app/shared/spreadsheet-util/spreadsheet-util.ts

@@ -608,7 +608,11 @@ export class SpreadsheetUtil {
 
         // If the cell does not have `v` property we ignore it, those are metadata properties
         if (cellValue && typeof cellValue === 'string') {
-          const potentialHeader = cellValue.toLowerCase()
+          // .trim(): header cells can pick up incidental leading/trailing
+          // whitespace from copy-pasting between spreadsheets/systems — treat
+          // that the same as the existing case-insensitive matching below,
+          // not as a genuinely different (missing) column.
+          const potentialHeader = cellValue.trim().toLowerCase()
           const headerIndex = csvArrayHeadersLower.indexOf(potentialHeader)
 
           if (headerIndex > -1) {