feat: add SAC app icon to favicon, sidebar, and login page

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/views/LoginView.vue

@@ -1,6 +1,10 @@
 <template>
-  <div class="card" style="max-width: 360px; margin: 4rem auto">
-    <h1 style="margin-top: 0">Вход в SAC</h1>
+  <div class="card login-card">
+    <div class="login-brand">
+      <img src="/sac-icon.png" alt="" class="login-brand-icon" width="64" height="64" />
+      <h1 class="login-title">Вход в SAC</h1>
+      <p class="login-subtitle">Security Alert Center</p>
+    </div>
     <form @submit.prevent="submit">
       <p>
         <label>Логин<br />
@@ -46,3 +50,34 @@ async function submit() {
   }
 }
 </script>
+
+<style scoped>
+.login-card {
+  max-width: 360px;
+  margin: 4rem auto;
+}
+
+.login-brand {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  text-align: center;
+  margin-bottom: 1.25rem;
+}
+
+.login-brand-icon {
+  border-radius: 12px;
+  margin-bottom: 0.75rem;
+}
+
+.login-title {
+  margin: 0;
+  font-size: 1.35rem;
+}
+
+.login-subtitle {
+  margin: 0.35rem 0 0;
+  color: #9aa4b2;
+  font-size: 0.9rem;
+}
+</style>