Add footer row label (F) in grid editor, matching header (H) style

Footer rows (e.g. page numbers) now show "F" in amber below the row
number, mirroring the blue "H" label for headers.

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

admin-lehrer/components/grid-editor/GridTable.tsx

@@ -292,6 +292,8 @@ export function GridTable({
                 className={`relative sticky left-0 z-10 flex items-center justify-center text-[10px] border-b border-r border-gray-200 dark:border-gray-700 cursor-pointer select-none transition-colors hover:bg-gray-100 dark:hover:bg-gray-700 ${
                   row.is_header
                     ? 'bg-blue-50 dark:bg-blue-900/20 text-blue-600 dark:text-blue-400 font-medium'
+                    : row.is_footer
+                    ? 'bg-amber-50 dark:bg-amber-900/20 text-amber-600 dark:text-amber-400 font-medium'
                     : 'bg-gray-50 dark:bg-gray-800/50 text-gray-400 dark:text-gray-500'
                 }`}
                 style={{ height: `${rowH}px` }}
@@ -300,6 +302,7 @@ export function GridTable({
               >
                 {row.index + 1}
                 {row.is_header && <span className="block text-[8px]">H</span>}
+                {row.is_footer && <span className="block text-[8px]">F</span>}
                 {/* Bottom-edge resize handle */}
                 <div
                   className="absolute bottom-0 left-0 w-full h-[4px] cursor-row-resize hover:bg-teal-400/40 z-20"

admin-lehrer/components/grid-editor/types.ts

@@ -83,6 +83,7 @@ export interface GridRow {
   y_min_pct: number
   y_max_pct: number
   is_header: boolean
+  is_footer?: boolean
 }
 
 export interface GridEditorCell {