add support for badges and notifications, adjust nav pages

lib/components/pages/logbook.dart

@@ -0,0 +1,48 @@
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+import 'package:mileograph_flutter/components/pages/legs.dart';
+import 'package:mileograph_flutter/components/pages/trips.dart';
+
+enum LogbookTab { entries, trips }
+
+class LogbookPage extends StatelessWidget {
+  const LogbookPage({super.key, this.initialTab = LogbookTab.entries});
+
+  final LogbookTab initialTab;
+
+  @override
+  Widget build(BuildContext context) {
+    final initialIndex = initialTab == LogbookTab.trips ? 1 : 0;
+    return DefaultTabController(
+      key: ValueKey(initialTab),
+      initialIndex: initialIndex,
+      length: 2,
+      child: Column(
+        children: [
+          TabBar(
+            onTap: (index) {
+              final dest =
+                  index == 0 ? '/logbook/entries' : '/logbook/trips';
+              final current = GoRouterState.of(context).uri.path;
+              if (current != dest) {
+                context.go(dest);
+              }
+            },
+            tabs: const [
+              Tab(text: 'Entries'),
+              Tab(text: 'Trips'),
+            ],
+          ),
+          Expanded(
+            child: TabBarView(
+              children: const [
+                LegsPage(),
+                TripsPage(),
+              ],
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}