add detail view

lib/widgets/detail_header_widget.dart

@@ -0,0 +1,76 @@
+import 'package:flutter/material.dart';
+import '../models/tank_model.dart';
+
+class DetailHeaderWidget extends StatelessWidget {
+  final TankModel tank;
+
+  const DetailHeaderWidget({super.key, required this.tank});
+
+  @override
+  Widget build(BuildContext context) {
+    return Card(
+      elevation: 4,
+      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(16)),
+      child: Container(
+        decoration: BoxDecoration(
+          gradient: LinearGradient(
+            begin: Alignment.topLeft,
+            end: Alignment.bottomRight,
+            colors: [Colors.green[600]!, Colors.green[800]!],
+          ),
+          borderRadius: BorderRadius.circular(16),
+        ),
+        padding: const EdgeInsets.all(24),
+        child: Row(
+          mainAxisAlignment: MainAxisAlignment.spaceBetween,
+          children: [
+            Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                Text(
+                  'Tankvorgang',
+                  style: TextStyle(
+                    color: Colors.white.withAlpha(230),
+                    fontSize: 14,
+                    fontWeight: FontWeight.w500,
+                  ),
+                ),
+                const SizedBox(height: 4),
+                Text(
+                  tank.szDate,
+                  style: const TextStyle(
+                    color: Colors.white,
+                    fontSize: 20,
+                    fontWeight: FontWeight.bold,
+                  ),
+                ),
+              ],
+            ),
+            Column(
+              crossAxisAlignment: CrossAxisAlignment.end,
+              children: [
+                Text(
+                  'Gesamtpreis',
+                  style: TextStyle(
+                    color: Colors.white.withAlpha(230),
+                    fontSize: 14,
+                    fontWeight: FontWeight.w500,
+                  ),
+                ),
+                const SizedBox(height: 4),
+                Text(
+                  '${tank.szPriceTotal}€',
+                  style: const TextStyle(
+                    color: Colors.white,
+                    fontSize: 28,
+                    fontWeight: FontWeight.bold,
+                  ),
+                ),
+              ],
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}