feat(form-builder): retry history table + integration (WS-6)

Per-attempt retry history (timestamp, user, outcome, exception detail
if failed) replaces the counter-only retry_count tracking.

Changes:

- New `form_submission_action_failure_retry_attempts` table (cascade on
  parent delete, nullOnDelete on user). Explicit short FK names
  (`fsafra_failure_fk`, `fsafra_user_fk`) — auto-generated names exceed
  MySQL's 64-char identifier limit.
- New FormSubmissionActionFailureRetryAttempt model + factory +
  succeeded() state.
- Parent FormSubmissionActionFailure gets retryAttempts() HasMany
  relation (latest('attempted_at')).
- New FormFailureRetryService centralises the retry-flow logic. Both
  the API controller and the artisan command delegate to it. Service
  writes a retry_attempt record per attempt; parent's retry_count
  stays as denormalised cache for index-view performance.
- Successful retry: attempt(succeeded) + parent.retry_count++ +
  parent.resolved_at + parent.resolved_by_user_id + parent.resolved_note
  ("Geslaagde retry door {actor.name}" or "Geslaagde retry
  (geautomatiseerd)" for command-line invocation without an actor).
- Failed retry: attempt(failed) with NEW exception details +
  parent.retry_count++. Parent's exception_class/_message stay
  audit-immutable — they represent the FIRST failure.
- canBeRetried() now correctly checks both resolved_at AND
  dismissed_at (sessie 2's open question Q2 closure).
- New FailureNotRetriableException (controller → 422) and
  ParentSubmissionGoneException (controller → 410) for cleaner
  flow control.

12 new tests:
- FormSubmissionActionFailureRetryAttemptTest (5 unit tests)
- RetryFlowProducesRetryAttemptsTest (7 integration tests covering
  succeeded path, failed path, resolved/dismissed blocking,
  multiple-retries chronological ordering, canBeRetried truth tables)

Pre-existing tests touched:
- FormSubmissionActionFailureTest::test_can_be_retried_only_for_open_state
  — updated to reflect Q2 closure (resolved now blocks too).
- Ws6FoundationMigrationTest::test_down_methods_clean_up_columns_and_table
  — child table must drop before parent (FK constraint).
- 5 backfill test step-counts bumped +1 (new migration sits at top).

SCHEMA.md → v2.9. Schema dump regenerated.

Refs: RFC-WS-6.md §3 Q5 addendum, sessie 2 Q2

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

api/tests/Feature/FormBuilder/Schema/Ws6FoundationMigrationTest.php

@@ -110,7 +110,13 @@ final class Ws6FoundationMigrationTest extends TestCase
         $applyStatus = require database_path(
             'migrations/2026_04_25_140000_extend_form_submissions_with_apply_status.php',
         );
+        // Sessie 3c added a child table referencing form_submission_action_failures
+        // via FK; we must drop the child before downing the parent.
+        $retryAttempts = require database_path(
+            'migrations/2026_04_28_180000_create_form_submission_action_failure_retry_attempts_table.php',
+        );
 
+        $retryAttempts->down();
         $createFailures->down();
         $applyStatus->down();
 
@@ -118,6 +124,7 @@ final class Ws6FoundationMigrationTest extends TestCase
             $this->assertFalse(Schema::hasColumn('form_submissions', 'apply_status'));
             $this->assertFalse(Schema::hasColumn('form_submissions', 'apply_completed_at'));
             $this->assertFalse(Schema::hasTable('form_submission_action_failures'));
+            $this->assertFalse(Schema::hasTable('form_submission_action_failure_retry_attempts'));
 
             $indexes = $this->indexNamesFor('form_submissions');
             $this->assertNotContains('fs_schema_apply_status_idx', $indexes);
@@ -126,6 +133,7 @@ final class Ws6FoundationMigrationTest extends TestCase
             // Restore state for any subsequent tests in this class.
             $applyStatus->up();
             $createFailures->up();
+            $retryAttempts->up();
         }
     }