SpreadsheetView: add bullet marker (•) for multi-line cells

Multi-line cells (containing \n) that don't already start with a
bullet character get • prepended in the frontend. This ensures
bullet points are visible regardless of whether the backend inserted
them (depends on when boxes were last rebuilt).

Skips header rows and cells that already have •, -, or – prefix.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

admin-lehrer/components/ocr-kombi/SpreadsheetView.tsx

@@ -85,7 +85,13 @@ function zoneToSheet(zone: GridZone, sheetIndex: number, isFirst: boolean): any
     }
 
     // Multi-line text (bullets with \n): enable text wrap + vertical top align
-    if (text.includes('\n')) {
+    // Add bullet marker (•) if multi-line and no bullet present
+    if (text.includes('\n') && !isHeader) {
+      if (!text.startsWith('•') && !text.startsWith('-') && !text.startsWith('–') && r > 0) {
+        text = '• ' + text
+        v.v = text
+        v.m = text
+      }
       v.tb = '2'  // text wrap
       v.vt = 0    // vertical align: top
     }