fix(fe): KsDataGrid - Enter key uses Tab navigation (suggestedNextCell)

Simplified navigateToNextCell to let Enter key use default AG Grid Tab behavior.

Previous: Custom Enter navigation (next editable column only)
New: Return suggestedNextCell for Enter, which is Tab's default behavior

This makes Enter and Tab fully equivalent, consistent with user expectation.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

frontend/src/shared/ui/components/KsDataGrid.vue

@@ -190,34 +190,10 @@ import type { NavigateToNextCellParams, CellPosition } from 'ag-grid-community'
 
 
 function navigateToNextCell(params: NavigateToNextCellParams): CellPosition | null {
-  const previousCell = params.previousCellPosition
   const suggestedNextCell = params.nextCellPosition
 
   if (params.key === 'Enter' || String(params.key) === '13') {
-    const allColumns = params.api.getAllGridColumns()
-    const editableCols = allColumns.filter(c => {
-      const colDef = c.getColDef()
-      return colDef.editable === true || typeof colDef.editable === 'function'
-    })
-
-    if (editableCols.length > 0) {
-      const currentColId = previousCell.column.getColId()
-      const currentIndex = editableCols.findIndex(c => c.getColId() === currentColId)
-
-      if (currentIndex >= 0 && currentIndex < editableCols.length - 1) {
-        const nextCol = editableCols[currentIndex + 1]
-        const colId = nextCol.getColId()
-        setTimeout(() => {
-          params.api.startEditingCell({ rowIndex: previousCell.rowIndex, colKey: colId })
-        }, 30)
-        return {
-          rowIndex: previousCell.rowIndex,
-          column: nextCol,
-          rowPinned: previousCell.rowPinned
-        }
-      }
-      return null
-    }
+    return suggestedNextCell
   }
 
   return suggestedNextCell