feat: registration form fields, section preferences, tag sync & schema updates

Implement EAV system for dynamic event-specific registration fields
with organisation-level templates, person section preferences with
priority ranking, and TagSyncService for deferred tag_picker sync.

New tables: registration_field_templates, registration_form_fields,
person_field_values, person_section_preferences.
New columns: persons.remarks, events.registration_show_section_preferences,
events.registration_show_availability.

58 tests, 126 assertions — all 432 tests pass (zero regressions).

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

api/app/Policies/RegistrationFormFieldPolicy.php

@@ -0,0 +1,84 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Policies;
+
+use App\Models\Event;
+use App\Models\RegistrationFormField;
+use App\Models\User;
+
+final class RegistrationFormFieldPolicy
+{
+    public function viewAny(User $user, Event $event): bool
+    {
+        return $this->belongsToOrganisation($user, $event);
+    }
+
+    public function view(User $user, RegistrationFormField $field, Event $event): bool
+    {
+        if ($field->event_id !== $event->id) {
+            return false;
+        }
+
+        return $this->belongsToOrganisation($user, $event);
+    }
+
+    public function create(User $user, Event $event): bool
+    {
+        return $this->canManageEvent($user, $event);
+    }
+
+    public function update(User $user, RegistrationFormField $field, Event $event): bool
+    {
+        if ($field->event_id !== $event->id) {
+            return false;
+        }
+
+        return $this->canManageEvent($user, $event);
+    }
+
+    public function delete(User $user, RegistrationFormField $field, Event $event): bool
+    {
+        if ($field->event_id !== $event->id) {
+            return false;
+        }
+
+        return $this->canManageEvent($user, $event);
+    }
+
+    public function reorder(User $user, Event $event): bool
+    {
+        return $this->canManageEvent($user, $event);
+    }
+
+    private function belongsToOrganisation(User $user, Event $event): bool
+    {
+        if ($user->hasRole('super_admin')) {
+            return true;
+        }
+
+        return $event->organisation->users()->where('user_id', $user->id)->exists();
+    }
+
+    private function canManageEvent(User $user, Event $event): bool
+    {
+        if ($user->hasRole('super_admin')) {
+            return true;
+        }
+
+        $isOrgAdmin = $event->organisation->users()
+            ->where('user_id', $user->id)
+            ->wherePivot('role', 'org_admin')
+            ->exists();
+
+        if ($isOrgAdmin) {
+            return true;
+        }
+
+        return $event->users()
+            ->where('user_id', $user->id)
+            ->wherePivot('role', 'event_manager')
+            ->exists();
+    }
+}