Add confirmation modal for project deletion

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/App.css

@@ -176,6 +176,60 @@ h2 {
   background: #e74c3c;
 }
 
+.modal-overlay {
+  position: fixed;
+  top: 0;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  background: rgba(0, 0, 0, 0.5);
+  display: flex;
+  justify-content: center;
+  align-items: center;
+  z-index: 100;
+}
+
+.modal {
+  background: white;
+  border-radius: 8px;
+  padding: 1.5rem 2rem;
+  min-width: 300px;
+  text-align: center;
+}
+
+.modal p {
+  font-size: 1.1rem;
+  margin-bottom: 1.5rem;
+}
+
+.modal-actions {
+  display: flex;
+  gap: 0.75rem;
+  justify-content: center;
+}
+
+.modal-actions button {
+  padding: 0.5rem 1.25rem;
+  font-size: 1rem;
+  cursor: pointer;
+  border: 1px solid #ccc;
+  border-radius: 4px;
+  background: #333;
+  color: white;
+}
+
+.modal-actions button:hover {
+  background: #555;
+}
+
+.modal-actions button.danger {
+  background: #c0392b;
+}
+
+.modal-actions button.danger:hover {
+  background: #e74c3c;
+}
+
 .vpn-block {
   display: flex;
   justify-content: center;