feat: registration form field display_width and option descriptions

Add configurable column widths (full/half) and optional descriptions
for radio/select/checkbox options on registration form fields.

- Migration adds display_width column to both tables
- FieldDisplayWidth enum with smart defaults per field type
- normalized_options accessor for backwards-compatible option format
- Portal form renderer uses display_width for VRow/VCol grid layout
- Radio/select/checkbox options render with descriptions
- Admin field editor supports display_width toggle and description input
- System templates updated with appropriate widths and descriptions

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

api/app/Models/RegistrationFieldTemplate.php

@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace App\Models;
 
+use App\Enums\FieldDisplayWidth;
 use App\Enums\RegistrationFieldType;
 use App\Models\Scopes\OrganisationScope;
 use Illuminate\Database\Eloquent\Builder;
@@ -36,6 +37,7 @@ final class RegistrationFieldTemplate extends Model
         'section',
         'help_text',
         'sort_order',
+        'display_width',
         'is_system',
         'is_active',
     ];
@@ -50,11 +52,31 @@ final class RegistrationFieldTemplate extends Model
             'is_portal_visible' => 'boolean',
             'is_admin_only' => 'boolean',
             'sort_order' => 'integer',
+            'display_width' => FieldDisplayWidth::class,
             'is_system' => 'boolean',
             'is_active' => 'boolean',
         ];
     }
 
+    /** @return array<int, array{label: string, description: string|null}>|null */
+    public function getNormalizedOptionsAttribute(): ?array
+    {
+        if ($this->options === null) {
+            return null;
+        }
+
+        return collect($this->options)->map(function (mixed $option): array {
+            if (is_string($option)) {
+                return ['label' => $option, 'description' => null];
+            }
+
+            return [
+                'label' => $option['label'] ?? (string) $option,
+                'description' => $option['description'] ?? null,
+            ];
+        })->toArray();
+    }
+
     public function organisation(): BelongsTo
     {
         return $this->belongsTo(Organisation::class);