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>

public/assets/js/modules/alert-dismiss.js

@@ -0,0 +1,18 @@
+(function () {
+  'use strict';
+  if (window.__alertDismissBound) {
+    return;
+  }
+  window.__alertDismissBound = true;
+
+  document.addEventListener('click', function (event) {
+    var btn = event.target.closest('[data-alert-dismiss]');
+    if (!btn) {
+      return;
+    }
+    var alert = btn.closest('[data-alert]');
+    if (alert && alert.parentNode) {
+      alert.parentNode.removeChild(alert);
+    }
+  });
+})();