feat(ui): heatmap view modes (all / jurist-reviewed / marked)

A segmented toggle over the heatmap: 'Alle' shows every evaluation,
'Geprüft (N)' filters to jurist-confirmed ones, 'Markiert' shows all
with a confirm-green check on the reviewed points. Jurists are
optional — the platform works without them and the default is 'Alle';
review only confirms a figure. Empty filtered view gets its own hint.

Signed-off-by: flemming-it <sf@flemming.it>

app/lib/widgets/heatmap_grid.dart

@@ -14,11 +14,16 @@ class HeatmapGrid extends StatefulWidget {
     super.key,
     required this.evaluations,
     this.onTap,
+    this.markReviewed = false,
   });
 
   final List<Evaluation> evaluations;
   final void Function(Evaluation)? onTap;
 
+  /// When true, points whose evaluation a jurist confirmed get a
+  /// confirm marker (used by the heatmap's "Markiert" view mode).
+  final bool markReviewed;
+
   @override
   State<HeatmapGrid> createState() => _HeatmapGridState();
 }
@@ -45,6 +50,7 @@ class _HeatmapGridState extends State<HeatmapGrid> {
               painter: _HeatmapPainter(
                 evaluations: widget.evaluations,
                 hoverIndex: _hoverIndex,
+                markReviewed: widget.markReviewed,
                 theme: Theme.of(context),
               ),
               size: size,
@@ -110,11 +116,13 @@ class _HeatmapPainter extends CustomPainter {
   _HeatmapPainter({
     required this.evaluations,
     required this.hoverIndex,
+    required this.markReviewed,
     required this.theme,
   });
 
   final List<Evaluation> evaluations;
   final int? hoverIndex;
+  final bool markReviewed;
   final ThemeData theme;
 
   @override
@@ -217,6 +225,33 @@ class _HeatmapPainter extends CustomPainter {
       canvas.drawCircle(c, r, body);
       canvas.drawCircle(c, r, ring);
 
+      // Jurist-confirmed marker (heatmap "Markiert" mode): a small
+      // confirm-green dot with a white check at the point's NE edge.
+      if (markReviewed && e.isReviewed) {
+        final m = Offset(c.dx + r * 0.72, c.dy - r * 0.72);
+        canvas.drawCircle(
+            m, 5.5, Paint()..color = ReclaimColors.reviewConfirmed);
+        canvas.drawCircle(
+            m,
+            5.5,
+            Paint()
+              ..color = theme.colorScheme.surface
+              ..style = PaintingStyle.stroke
+              ..strokeWidth = 1.5);
+        final check = Path()
+          ..moveTo(m.dx - 2.4, m.dy + 0.2)
+          ..lineTo(m.dx - 0.6, m.dy + 2.0)
+          ..lineTo(m.dx + 2.6, m.dy - 2.2);
+        canvas.drawPath(
+            check,
+            Paint()
+              ..color = theme.colorScheme.surface
+              ..style = PaintingStyle.stroke
+              ..strokeWidth = 1.4
+              ..strokeCap = StrokeCap.round
+              ..strokeJoin = StrokeJoin.round);
+      }
+
       _drawText(
         canvas,
         '${e.norm.jurabk} ${e.norm.paragraph}',
@@ -303,5 +338,6 @@ class _HeatmapPainter extends CustomPainter {
   @override
   bool shouldRepaint(covariant _HeatmapPainter old) =>
       old.hoverIndex != hoverIndex ||
+      old.markReviewed != markReviewed ||
       old.evaluations.length != evaluations.length;
 }