Added Provider and DetailPage

lib/pages/detail_checklist_page.dart

@@ -1,10 +1,56 @@
+import 'package:briessenchecker/models/checklist.dart';
+import 'package:briessenchecker/services/checklist_provider.dart';
+import 'package:briessenchecker/services/dbhelper.dart';
 import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
 
-class DetailChecklistPage extends StatelessWidget {
+class DetailChecklistPage extends StatefulWidget {
   const DetailChecklistPage({super.key});
   static const routeName = '/detail';
+
+  @override
+  State<DetailChecklistPage> createState() => _DetailChecklistPageState();
+}
+
+class _DetailChecklistPageState extends State<DetailChecklistPage> {
+  late final ChecklistProvider checklistProvider;
+  late Future<Checklist> checklistFuture;
+
+  @override
+  void initState() {
+    super.initState();
+    checklistProvider = Provider.of<ChecklistProvider>(context, listen: false);
+    checklistFuture =
+        DbHelper.getChecklistById(checklistProvider.selectedChecklistId!);
+  }
+
+  @override
+  void dispose() {
+    super.dispose();
+    checklistProvider.updateSelectedChecklist(null, silent: true);
+  }
+
   @override
   Widget build(BuildContext context) {
-    return const Placeholder();
+    return Scaffold(
+      body: FutureBuilder(
+        future: checklistFuture,
+        builder: _futureBuilder,
+      ),
+    );
+  }
+
+  Widget _futureBuilder(
+      BuildContext context, AsyncSnapshot<Checklist> snapshot) {
+    if (snapshot.hasData) {
+      return Column(
+        children: [
+          Text(snapshot.data!.title),
+          Text(snapshot.data!.description),
+        ],
+      );
+    } else {
+      return const CircularProgressIndicator();
+    }
   }
 }