feat: passwordless registration — defer account creation to approval

Removes password from the volunteer registration form. Account
creation is now deferred to the approval step:

Backend:
- Registration creates Person without User (user_id=null)
- On approval, system finds or creates User by person.email
- New accounts get a "set password" email with activation link
- Existing accounts get a portal link email
- Added registration_source column to persons (self/organizer)
- Fuzzy name matching skipped for self-registered persons
- person.email is always source of truth for account linking

Frontend:
- Registration form no longer collects password
- Email check shows info alert with login suggestion
- New wachtwoord-instellen.vue page for account activation
- PasswordRequirements.vue component (reused on reset page)
- Success page updated with activation messaging

Tests: 837 passed (all updated for new flow)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/database/factories/PersonFactory.php

@@ -61,4 +61,14 @@ final class PersonFactory extends Factory
     {
         return $this->state(fn () => ['status' => 'rejected']);
     }
+
+    public function selfRegistered(): static
+    {
+        return $this->state(fn () => ['registration_source' => 'self']);
+    }
+
+    public function organizerCreated(): static
+    {
+        return $this->state(fn () => ['registration_source' => 'organizer']);
+    }
 }

api/database/migrations/2026_04_17_100000_add_registration_source_to_persons_table.php

@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+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('persons', function (Blueprint $table) {
+            $table->string('registration_source', 20)->default('organizer')->after('status');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('persons', function (Blueprint $table) {
+            $table->dropColumn('registration_source');
+        });
+    }
+};