fix(auth): scope email uniqueness to active users

database/migrations/2026_09_03_000100_scope_user_email_unique_to_active_accounts.php

@@ -0,0 +1,28 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::table('users', function (Blueprint $table): void {
+            $table->dropUnique(['email']);
+            $table->string('active_email')
+                ->nullable()
+                ->storedAs('CASE WHEN `deleted_at` IS NULL THEN LOWER(`email`) ELSE NULL END');
+            $table->unique('active_email');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('users', function (Blueprint $table): void {
+            $table->dropUnique(['active_email']);
+            $table->dropColumn('active_email');
+            $table->unique('email');
+        });
+    }
+};