feat: aggiunge drag & drop di cartelle e file zip per lo smistamento

renderer/index.html

@@ -92,6 +92,29 @@
         background: #f8fafc;
       }
 
+      .drop-zone {
+        margin-top: 18px;
+        border: 2px dashed #9db4d8;
+        border-radius: 12px;
+        background: #f2f7ff;
+        color: #1e3a5f;
+        padding: 20px;
+        text-align: center;
+        font-size: 14px;
+        transition: border-color 120ms ease, background-color 120ms ease, color 120ms ease;
+      }
+
+      .drop-zone.active {
+        border-color: var(--accent);
+        background: #e8f0ff;
+      }
+
+      .drop-zone.error {
+        border-color: #dc2626;
+        background: #fff1f2;
+        color: #991b1b;
+      }
+
       .rules h2 {
         margin: 0 0 10px;
         font-size: 17px;
@@ -166,6 +189,10 @@
         <button id="zipBtn" class="secondary">Process ZIP</button>
       </div>
 
+      <section class="drop-zone" id="dropZone">
+        Trascina qui una cartella o un file .zip
+      </section>
+
       <section class="rules">
         <h2>Destinazione file CAD</h2>
         <div class="rule-row single-row">