refactor: fix 7 CRUD system inconsistencies for robustness and maintainability

- Add user-assignment dependency check to DepartmentService.deleteByUuid (409 when users assigned)
- Standardize POST detection to isMethod('POST') in 10 create/edit actions
- Align RoleService code uniqueness to warning pattern (matching departments)
- Normalize repository create() return types from mixed to int|false (3 repos + 3 interfaces)
- Add JSON response branches to 4 non-user delete actions
- Document delete authorization ordering pattern
- Decompose AdminSettingsService.updateFromAdmin into domain-scoped private methods

Workflow: .agents/runs/CRUD-CONSISTENCY-001/
Reviewed by: Code Reviewer (pass), Security Reviewer (pass), Acceptance Tester (pass)
Quality gates: QG-001 PHPUnit pass, QG-002 PHPStan pass, QG-003 Architecture pass

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

pages/admin/roles/create(default).phtml

@@ -42,6 +42,15 @@
     $validationSummaryErrors = $validationSummaryErrors ?? ($errors ?? []);
     require templatePath('partials/app-details-validation-summary.phtml');
     ?>
+    <?php if (!empty($warnings)): ?>
+      <div class="notice" data-variant="info">
+        <ul>
+          <?php foreach ($warnings as $warning): ?>
+            <li><?php e($warning); ?></li>
+          <?php endforeach; ?>
+        </ul>
+      </div>
+    <?php endif; ?>
     <?php
     $values = $form ?? [];
     $detailsOpenAll = true;