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/settings/email-mailboxes.php

@@ -17,10 +17,10 @@ $isEdit = $em !== null;
   <p class="muted mt-12">Konfiguracja skrzynek SMTP do wysylki wiadomosci e-mail.</p>
 
   <?php if (!empty($errorMessage)): ?>
-    <div class="alert alert--danger mt-12" role="alert"><?= $e((string) $errorMessage) ?></div>
+    <div class="mt-12"><?php $type='danger'; $message=(string) $errorMessage; $dismissible=true; include dirname(__DIR__) . '/components/alert.php'; ?></div>
   <?php endif; ?>
   <?php if (!empty($successMessage)): ?>
-    <div class="alert alert--success mt-12" role="status"><?= $e((string) $successMessage) ?></div>
+    <div class="mt-12"><?php $type='success'; $message=(string) $successMessage; $dismissible=true; include dirname(__DIR__) . '/components/alert.php'; ?></div>
   <?php endif; ?>
 </section>