feat(form-builder): ApplyBindings listener chain with two-transaction pattern (WS-6)

ApplyBindingsOnFormSubmit (sync) wraps the applicator in DB::transaction
and writes apply_status post-commit. On exception: outer catch records
FormSubmissionActionFailure in a separate transaction (survives inner
rollback), marks apply_status=failed, swallows so siblings keep running
(RFC Q3, Q4). When ApplyBindings provisions a Person on a previously
no-subject submission, the listener also writes subject_type/subject_id
back so TriggerPersonIdentityMatchOnFormSubmit (next sync listener) can
find the freshly-provisioned subject.

ApplyBindingsOnFormSectionSubmitted (queued, feature-flagged) ready
for ARTIST_ADVANCE activation per RFC Q10.

Listener chain on FormSubmissionSubmitted explicitly registered in
AppServiceProvider::boot for deterministic ordering (RFC Q1):
ApplyBindings → IdentityMatch → queued siblings.

FormBindingApplicator dropped 'final readonly' to 'class' so listener
tests can subclass it for throw-path coverage; constructor properties
remain readonly individually.

Refs: RFC-WS-6.md §3 (Q1, Q3, Q4, Q10)

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

api/app/FormBuilder/Bindings/FormBindingApplicator.php

@@ -27,13 +27,17 @@ use Throwable;
  *   - Q10: optional sectionId for future section-level apply.
  *   - Q12: hierarchical activity log via BindingActivityLogger.
  */
-final readonly class FormBindingApplicator
+// Not final + not readonly: listener tests need to override `apply()` for
+// throw-path coverage (Mockery can't mock final classes; PHP doesn't allow
+// extending readonly with non-readonly child). Properties stay readonly
+// individually to preserve immutability.
+class FormBindingApplicator
 {
     public function __construct(
-        private PurposeRegistry $purposeRegistry,
-        private BindingConflictResolver $conflictResolver,
-        private BindingTypeRegistry $typeRegistry,
-        private BindingActivityLogger $activityLogger,
+        private readonly PurposeRegistry $purposeRegistry,
+        private readonly BindingConflictResolver $conflictResolver,
+        private readonly BindingTypeRegistry $typeRegistry,
+        private readonly BindingActivityLogger $activityLogger,
     ) {}
 
     /**