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/scss/shared/_ui-components.scss

@@ -140,11 +140,67 @@
 }
 
 .alert {
+  display: flex;
+  align-items: flex-start;
+  gap: 10px;
   padding: 12px 14px;
   border-radius: 8px;
   border: 1px solid transparent;
   font-size: 13px;
   min-height: 44px;
+  line-height: 1.4;
+
+  &__icon {
+    flex: 0 0 18px;
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+    width: 18px;
+    height: 18px;
+    line-height: 1;
+    color: inherit;
+
+    svg {
+      width: 18px;
+      height: 18px;
+      display: block;
+    }
+  }
+
+  &__body {
+    flex: 1;
+    min-width: 0;
+    word-break: break-word;
+  }
+
+  &__dismiss {
+    flex: 0 0 auto;
+    margin-left: auto;
+    align-self: flex-start;
+    background: transparent;
+    border: 0;
+    padding: 2px 6px;
+    cursor: pointer;
+    color: inherit;
+    opacity: 0.55;
+    font-size: 16px;
+    line-height: 1;
+    border-radius: 4px;
+    transition: opacity 0.15s ease, background-color 0.15s ease;
+
+    &:hover,
+    &:focus-visible {
+      opacity: 1;
+      background-color: rgba(0, 0, 0, 0.06);
+      outline: none;
+    }
+  }
+}
+
+.alert--info {
+  border-color: #bfdbfe;
+  background: #eff6ff;
+  color: #1e3a8a;
 }
 
 .alert--danger {
@@ -165,6 +221,13 @@
   color: #815500;
 }
 
+.alerts-stack {
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+  margin-bottom: 12px;
+}
+
 .form-field {
   display: grid;
   gap: 5px;