feat(120): alert component unification

Phase 120 - Plan 01:
- Reusable PHP alert component (resources/views/components/alert.php)
  with inline SVG icon per type, optional dismiss button.
- Missing .alert--info SCSS variant added (#eff6ff/#bfdbfe/#1e3a8a) -
  fixes black-on-white alert after Fakturownia test connection.
- Flash::push(type, message) + Flash::all() with BC for set/get;
  legacy key heuristic (error/.save/warning -> typed entries).
- Central flash renderer in 3 layouts (app/auth/public) iterating
  Flash::all() through component (.alerts-stack wrap).
- Vanilla JS alert-dismiss.js with idempotent guard and delegated
  click handler on [data-alert-dismiss].
- 36 views migrated off inline <div class="alert alert--TYPE">;
  .flash--error/success removed from views (orders/show, shipments/prepare).
- SCSS rebuilt: public/assets/css/{app,login}.css.

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

resources/views/layouts/auth.php

@@ -14,7 +14,19 @@
   <div class="bg-orb bg-orb-right" aria-hidden="true"></div>
 
   <main class="login-page">
+    <?php $flashEntries = \App\Core\Support\Flash::all(); ?>
+    <?php if (!empty($flashEntries)): ?>
+      <div class="alerts-stack" data-flash-stack>
+        <?php foreach ($flashEntries as $flashEntry): ?>
+          <?php $type = (string) ($flashEntry['type'] ?? 'info'); ?>
+          <?php $message = (string) ($flashEntry['message'] ?? ''); ?>
+          <?php $dismissible = true; ?>
+          <?php include __DIR__ . '/../components/alert.php'; ?>
+        <?php endforeach; ?>
+      </div>
+    <?php endif; ?>
     <?= $content ?>
   </main>
+  <script src="/assets/js/modules/alert-dismiss.js?ver=<?= filemtime(dirname(__DIR__, 3) . '/public/assets/js/modules/alert-dismiss.js') ?: 0 ?>"></script>
 </body>
 </html>