test(form-builder): cover purpose registry and morph-map alignment

- PurposeRegistryTest: all seven purposes load with expected shape;
  `get()` throws PurposeNotFoundException on unknown slug;
  `allSubjectTypes()` returns exactly [artist, company, person, user];
  `publicAccessibleSlugs()` is only `[event_registration]`.
- PurposeSchemaLifecycleTest: data-provider-driven create → publish
  for all seven purposes; negative tests for event_registration (three
  missing bindings) and supplier_intake (company.name missing); partial
  binding test reports only the missing subset.
- CustomPurposeEscapeRemovedTest: column gone, config file gone,
  FormPurpose::CUSTOM gone, store endpoint rejects `'custom'`, resource
  payload omits the field.
- SubjectTypeRegistryConsolidationTest: submission validation accepts
  registry subject types, rejects everything else including the legacy
  `event` alias that used to be allowed.
- MorphMapAlignmentTest: compile-time guard that every
  PurposeRegistry::allSubjectTypes() alias appears in the morph-map and
  in AppServiceProvider::PURPOSE_SUBJECT_FQCN.
- FormPurposeTest rewritten to cover the seven v1.0 cases and the
  registry-delegation helpers (now extends Tests\TestCase for the
  container).
- Public/listener tests swap the removed PUBLIC_RSVP / PUBLIC_COMPLAINT
  / FEEDBACK references for valid v1.0 purposes, preserving their
  negative-path assertions.

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

api/tests/Feature/FormBuilder/PublicFormApiTest.php

@@ -30,7 +30,7 @@ final class PublicFormApiTest extends TestCase
         $this->org = Organisation::factory()->create();
         $this->schema = FormSchema::factory()->create([
             'organisation_id' => $this->org->id,
-            'purpose' => FormPurpose::PUBLIC_RSVP,
+            'purpose' => FormPurpose::EVENT_REGISTRATION,
             'is_published' => true,
             'public_token' => (string) Str::ulid(),
         ]);