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/auth_provider.dart

@@ -0,0 +1,82 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:firebase_auth/firebase_auth.dart';
+import '../services/auth_service.dart';
+import '../models/user_model.dart';
+
+// Auth service provider
+final authServiceProvider = Provider<AuthService>((ref) => AuthService());
+
+// Auth state provider - lytter til Firebase Auth state changes
+final authStateProvider = StreamProvider<User?>((ref) {
+  final authService = ref.watch(authServiceProvider);
+  return authService.authStateChanges;
+});
+
+// Current user provider
+final currentUserProvider = Provider<User?>((ref) {
+  final authState = ref.watch(authStateProvider);
+  return authState.when(
+    data: (user) => user,
+    loading: () => null,
+    error: (_, __) => null,
+  );
+});
+
+// User data provider - henter brukerdata fra Firestore
+final userDataProvider = StreamProvider<UserModel?>((ref) {
+  final user = ref.watch(currentUserProvider);
+  if (user == null) {
+    return Stream.value(null);
+  }
+  final authService = ref.watch(authServiceProvider);
+  return authService.userDataStream(user.uid);
+});
+
+// Login provider
+final loginProvider = Provider<Future<UserCredential> Function({
+  required String email,
+  required String password,
+})>((ref) {
+  final authService = ref.watch(authServiceProvider);
+  return ({required String email, required String password}) {
+    return authService.signInWithEmail(email: email, password: password);
+  };
+});
+
+// Sign up provider
+final signUpProvider = Provider<Future<UserCredential> Function({
+  required String email,
+  required String password,
+  required String displayName,
+  required String organizationId,
+  String? departmentId,
+})>((ref) {
+  final authService = ref.watch(authServiceProvider);
+  return ({
+    required String email,
+    required String password,
+    required String displayName,
+    required String organizationId,
+    String? departmentId,
+  }) {
+    return authService.signUpWithEmail(
+      email: email,
+      password: password,
+      displayName: displayName,
+      organizationId: organizationId,
+      departmentId: departmentId,
+    );
+  };
+});
+
+// Sign out provider
+final signOutProvider = Provider<Future<void> Function()>((ref) {
+  final authService = ref.watch(authServiceProvider);
+  return () => authService.signOut();
+});
+
+// Reset password provider
+final resetPasswordProvider = Provider<Future<void> Function(String)>((ref) {
+  final authService = ref.watch(authServiceProvider);
+  return (String email) => authService.resetPassword(email);
+});