Initial commit: TimeReg Flutter app med Firebase backend

- Opprettet Flutter-prosjekt med alle nødvendige avhengigheter
- Implementert datamodeller (User, TimeRegistration, TariffProfile, Deviation, AuditLog)
- Implementert tjenester (AuthService, TimeService)
- Implementert Riverpod providers for state management
- Opprettet autentiseringsskjermer (login, signup, reset password)
- Opprettet hjemmeskjerm med timer-funksjonalitet
- Opprettet placeholder-skjermer for historikk, rapporter og profil
- Lagt til norsk dokumentasjon i README

lib/providers/time_provider.dart

@@ -0,0 +1,86 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import '../services/time_service.dart';
+import '../models/time_registration.dart';
+import 'auth_provider.dart';
+
+// Time service provider
+final timeServiceProvider = Provider<TimeService>((ref) => TimeService());
+
+// Active registration provider - henter pågående timeregistrering
+final activeRegistrationProvider = FutureProvider<TimeRegistration?>((ref) async {
+  final user = ref.watch(currentUserProvider);
+  if (user == null) return null;
+  
+  final timeService = ref.watch(timeServiceProvider);
+  return timeService.getActiveRegistration(user.uid);
+});
+
+// Today's registrations provider
+final todayRegistrationsProvider = StreamProvider<List<TimeRegistration>>((ref) {
+  final user = ref.watch(currentUserProvider);
+  if (user == null) {
+    return Stream.value([]);
+  }
+  
+  final timeService = ref.watch(timeServiceProvider);
+  final today = DateTime.now();
+  final startOfDay = DateTime(today.year, today.month, today.day);
+  final endOfDay = DateTime(today.year, today.month, today.day, 23, 59, 59);
+  
+  return timeService.registrationsStream(
+    userId: user.uid,
+    startDate: startOfDay,
+    endDate: endOfDay,
+  );
+});
+
+// Registrations for date range provider
+final registrationsProvider = FutureProvider.family<List<TimeRegistration>, DateRange>(
+  (ref, dateRange) async {
+    final user = ref.watch(currentUserProvider);
+    if (user == null) return [];
+    
+    final timeService = ref.watch(timeServiceProvider);
+    return timeService.getRegistrations(
+      userId: user.uid,
+      startDate: dateRange.start,
+      endDate: dateRange.end,
+    );
+  },
+);
+
+// Total hours for period provider
+final totalHoursProvider = FutureProvider.family<Map<String, int>, DateRange>(
+  (ref, dateRange) async {
+    final user = ref.watch(currentUserProvider);
+    if (user == null) {
+      return {'total': 0, 'ordinary': 0, 'overtime': 0};
+    }
+    
+    final timeService = ref.watch(timeServiceProvider);
+    return timeService.calculateTotalHours(
+      userId: user.uid,
+      startDate: dateRange.start,
+      endDate: dateRange.end,
+    );
+  },
+);
+
+// Helper class for date ranges
+class DateRange {
+  final DateTime start;
+  final DateTime end;
+  
+  DateRange({required this.start, required this.end});
+  
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is DateRange &&
+          runtimeType == other.runtimeType &&
+          start == other.start &&
+          end == other.end;
+  
+  @override
+  int get hashCode => start.hashCode ^ end.hashCode;
+}