ui: refina visual do header, aumenta avatar da kemily e altera icone de anexo

public/index.html

@@ -197,8 +197,8 @@
           <form id="chatForm">
             <div class="input-box">
               <button type="button" id="btnAttach" class="btn-attach" aria-label="Anexar arquivo" title="Anexar imagem ou documento">
-                <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke-width="2" stroke="currentColor">
-                  <path stroke-linecap="round" stroke-linejoin="round" d="m15.75 10.5 4.72-4.72a.75.75 0 0 1 1.28.53v11.38a.75.75 0 0 1-1.28.53l-4.72-4.72M4.5 18.75h9a2.25 2.25 0 0 0 2.25-2.25v-9a2.25 2.25 0 0 0-2.25-2.25h-9A2.25 2.25 0 0 0 2.25 7.5v9a2.25 2.25 0 0 0 2.25 2.25Z" />
+                <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor">
+                  <path stroke-linecap="round" stroke-linejoin="round" d="m18.375 12.739-7.693 7.693a4.5 4.5 0 0 1-6.364-6.364l10.94-10.94A3 3 0 1 1 19.5 7.372L8.552 18.32m.009-.01-.01.01m5.699-9.941-7.81 7.81a1.5 1.5 0 0 0 2.112 2.13" />
                 </svg>
               </button>
               <input type="file" id="fileInput" accept="image/*,.pdf,.doc,.docx,.txt" multiple style="display:none">

public/style.css

@@ -781,7 +781,7 @@ body {
   cursor: pointer;
   padding: 8px;
   border-radius: 8px;
-  display: flex;
+  display: none; /* Oculto por padrão no desktop */
   align-items: center;
   justify-content: center;
   transition: color var(--transition-fast), background-color var(--transition-fast);
@@ -798,7 +798,7 @@ body {
 }
 
 .model-badge {
-  display: flex;
+  display: none !important; /* Oculto conforme solicitação do usuário */
   align-items: center;
   gap: 6px;
   padding: 6px 12px;
@@ -1420,6 +1420,9 @@ code {
    MEDIA QUERIES (RESPONSIVIDADE MOBILE-FIRST)
    ========================================================================== */
 @media (max-width: 768px) {
+  .btn-menu {
+    display: flex;
+  }
   /* No Mobile, a Sidebar fica escondida por padrão e abre em overlay */
   .sidebar {
     position: absolute;
@@ -1554,8 +1557,8 @@ code {
 
 /* Welcome Logo Avatar */
 .welcome-avatar-wrapper {
-  width: 72px;
-  height: 72px;
+  width: 86px;
+  height: 86px;
   border-radius: 50%;
   overflow: hidden;
   border: 2px solid rgba(16, 163, 127, 0.3);