fix: Box-Zone Clamping nach Box-Mitte statt Cell-Center entscheiden

Euro/Badge-Zeilen hatten ihren Center innerhalb der Box-Zone, weshalb
das Clamping nicht griff. Jetzt wird anhand der Box-Mitte entschieden
ob eine Zelle nach oben (clamp height) oder unten (push y) gehoert.

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

admin-lehrer/components/ocr-pipeline/StepReconstruction.tsx

@@ -501,18 +501,18 @@ export function StepReconstruction({ sessionId, onNext }: StepReconstructionProp
 
     const cellTop = bboxPct.y
     const cellBottom = bboxPct.y + bboxPct.h
-    const cellCenter = cellTop + bboxPct.h / 2
+    const boxMid = (boxZonesPct[0].topPct + boxZonesPct[0].bottomPct) / 2
 
     for (const { topPct, bottomPct } of boxZonesPct) {
-      // Cell ABOVE box: clamp height so bottom doesn't exceed box top
-      if (cellCenter < topPct && cellBottom > topPct) {
-        return { ...bboxPct, h: topPct - cellTop }
-      }
-      // Cell BELOW box: push top down to box bottom
-      if (cellCenter > bottomPct && cellTop < bottomPct) {
-        const newY = bottomPct
-        return { ...bboxPct, y: newY, h: cellBottom - newY }
+      // Check if cell overlaps with box zone at all
+      if (cellBottom <= topPct || cellTop >= bottomPct) continue
+
+      // Cell starts ABOVE box midpoint → belongs above, clamp bottom to box top
+      if (cellTop < boxMid) {
+        return { ...bboxPct, h: Math.max(0.5, topPct - cellTop) }
       }
+      // Cell starts AT or BELOW box midpoint → belongs below, push top to box bottom
+      return { ...bboxPct, y: bottomPct, h: Math.max(0.5, cellBottom - bottomPct) }
     }
     return bboxPct
   }