feat(form-builder): API resources with FieldAccessService filtering

Phase 4 of S2b. Nine resources that shape the universal form builder
responses. FieldAccessService::filterVisibleFields gates every field
array — the primary defence tested by FormResourceSecurityTest (§22.9).

- FormSchemaResource: includes fields_count, submissions_count,
  has_submissions, is_locked (derived from edit_lock_*), public_form_url
  when public_token is set, and filtered fields collection.
- FormSchemaSummaryResource: lean list-endpoint variant.
- FormFieldResource: effective_label / help_text / options resolved via
  FormLocaleResolver + translations JSON, plus TAG_PICKER available_tags
  filtered by validation_rules.tag_categories.
- FormSubmissionResource: values keyed by field slug with FieldAccessService
  filtering, section_statuses, active delegations, review_info,
  submitted_in_locale, submission_duration_seconds.
- FormSubmissionSummaryResource: lean list variant.
- FormTemplateResource, FormFieldLibraryResource.
- PublicFormSchemaResource: strictly limited per §10 — only
  is_portal_visible=true AND is_admin_only=false fields, no PII hints,
  no role_restrictions, no submissions_count.
- FormSchemaWebhookResource: url/secret never returned; only url_host +
  has_secret boolean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

api/app/Http/Resources/FormBuilder/FormSchemaWebhookResource.php

@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Resources\FormBuilder;
+
+use App\Models\FormBuilder\FormSchemaWebhook;
+use Illuminate\Http\Request;
+use Illuminate\Http\Resources\Json\JsonResource;
+
+/**
+ * Never exposes the raw URL or secret — only the host + has_secret flag.
+ *
+ * @mixin FormSchemaWebhook
+ */
+final class FormSchemaWebhookResource extends JsonResource
+{
+    /**
+     * @return array<string, mixed>
+     */
+    public function toArray(Request $request): array
+    {
+        $urlHost = null;
+        if (! empty($this->url)) {
+            $parts = parse_url((string) $this->url);
+            $urlHost = $parts['host'] ?? null;
+        }
+
+        return [
+            'id' => $this->id,
+            'form_schema_id' => $this->form_schema_id,
+            'name' => $this->name,
+            'trigger_event' => $this->trigger_event,
+            'url_host' => $urlHost,
+            'has_secret' => ! empty($this->secret),
+            'is_active' => (bool) $this->is_active,
+            'created_at' => optional($this->created_at)->toIso8601String(),
+            'updated_at' => optional($this->updated_at)->toIso8601String(),
+        ];
+    }
+}