Adds code for the callback for floating app window, and fixes Trip End time not being initialized.

lib/main.dart

@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:io';
 
 import 'package:flutter/material.dart';
@@ -6,6 +7,16 @@ import 'package:timetrack/consts.dart';
 import 'package:timetrack/data.dart';
 import 'package:timetrack/pages/MainApp.dart';
 
+@pragma("vm:entry-point")
+void serviceEntry() {
+  // This is where both the Background service and the Floating app window would enter the app.
+  Timer.periodic(Duration(seconds: 5), (timer) async {
+    // Run the location fetch, add to list, etc, etc.
+  });
+
+  // Run the floater app here.
+}
+
 Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();