feat: Implement initial authentication, multi-environment support, and core app infrastructure.

lib/core/constants/api_constants.dart

@@ -0,0 +1,13 @@
+class ApiConstants {
+  ApiConstants._();
+
+  static const String authRegister = '/auth/register';
+  static const String authLogin = '/auth/login';
+  static const String authForgotPassword = '/auth/forgot-password';
+  static const String authResetPassword = '/auth/reset-password';
+  static const String authVerifyEmail = '/auth/verify-email';
+  static const String authResendVerification = '/auth/resend-verification';
+  static const String authMe = '/auth/me';
+  static const String authRefresh = '/auth/refresh';
+  static const String authLogout = '/auth/logout';
+}

lib/core/constants/app_colors.dart

@@ -0,0 +1,20 @@
+import 'package:flutter/material.dart';
+
+class AppColors {
+  AppColors._();
+
+  static const Color primaryDark = Color(0xFF00293D);
+  static const Color accentOrange = Color(0xFFE58625);
+  static const Color accentOrangeHover = Color(0xFFD47A1F);
+  static const Color gradientStart = Color(0xFFC4D9D4);
+  static const Color gradientEnd = Color(0xFFF0F5FC);
+  static const Color inputFill = Color(0xFFF0F5FC);
+  static const Color white = Color(0xFFFFFFFF);
+  static const Color error = Color(0xFFDC2626);
+  static const Color errorBg = Color(0xFFFEF2F2);
+  static const Color errorBorder = Color(0xFFFECACA);
+  static const Color success = Color(0xFF22C55E);
+  static const Color divider = Color(0x3300293D); // 20% opacity
+  static const Color hintText = Color(0x9900293D); // 60% opacity
+  static const Color subtleText = Color(0x7000293D); // ~44% opacity
+}