feat(auth): transition from email to phone-based OTP authentication

- Replace Email+Password login with Phone+OTP flow
- Remove RegisterCubit and registration screens (email verification)
- Remove ResetPasswordCubit and reset password screens
- Add phone normalization and international dial code support
- Update LoginCubit with sendCode/resend cooldown logic
- Add new widgets: phone prefix selector, confirm sheet
- Update all auth API endpoints: /otp/send, /phone-session
- Update form inputs: Email -> Phone with E.164 validation
- Update tests for new auth flow

apps/lib/features/auth/ui/widgets/auth_field.dart

@@ -1,41 +1,48 @@
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 
 import '../../../../core/theme/design_tokens.dart';
 
 class AuthField extends StatelessWidget {
   const AuthField({
     super.key,
-    required this.label,
+    this.label,
     required this.hint,
     required this.controller,
     this.keyboardType,
     this.obscureText = false,
     this.suffixIcon,
     this.onChanged,
+    this.prefix,
+    this.inputFormatters,
   });
 
-  final String label;
+  final String? label;
   final String hint;
   final TextEditingController controller;
   final TextInputType? keyboardType;
   final bool obscureText;
   final Widget? suffixIcon;
   final ValueChanged<String>? onChanged;
+  final Widget? prefix;
+  final List<TextInputFormatter>? inputFormatters;
 
   @override
   Widget build(BuildContext context) {
     return Column(
       crossAxisAlignment: CrossAxisAlignment.start,
       children: [
-        Text(
-          label,
-          style: const TextStyle(
-            fontSize: 13,
-            fontWeight: FontWeight.w700,
-            color: AppColors.slate700,
+        if (label != null) ...[
+          Text(
+            label!,
+            style: const TextStyle(
+              fontSize: 13,
+              fontWeight: FontWeight.w700,
+              color: AppColors.slate700,
+            ),
           ),
-        ),
-        SizedBox(height: AppSpacing.sm),
+          SizedBox(height: AppSpacing.sm),
+        ],
         Semantics(
           label: label,
           textField: true,
@@ -44,6 +51,7 @@ class AuthField extends StatelessWidget {
             keyboardType: keyboardType,
             obscureText: obscureText,
             onChanged: onChanged,
+            inputFormatters: inputFormatters,
             style: const TextStyle(fontSize: 16, color: AppColors.slate900),
             decoration: InputDecoration(
               hintText: hint,
@@ -57,6 +65,7 @@ class AuthField extends StatelessWidget {
                 horizontal: AppSpacing.lg,
                 vertical: AppSpacing.lg,
               ),
+              prefixIcon: prefix,
               suffixIcon: suffixIcon,
               border: OutlineInputBorder(
                 borderRadius: BorderRadius.circular(AppRadius.lg),