Fix unused-result warning on dropDestination handlers

SwiftUI's dropDestination(for:action:) action closure is Void-
returning, not Bool, so handleDrop's Bool return was being silently
discarded — made the discard explicit with _ =.

oAI/Views/Main/SidebarView.swift

@@ -150,7 +150,7 @@ struct SidebarView: View {
                         } header: {
                             Text("Unfiled")
                                 .dropDestination(for: String.self) { items, _ in
-                                    handleDrop(items, toFolder: nil)
+                                    _ = handleDrop(items, toFolder: nil)
                                 }
                         }
                     }
@@ -192,7 +192,7 @@ struct SidebarView: View {
             }
         }
         .dropDestination(for: String.self) { items, _ in
-            handleDrop(items, toFolder: folder.id)
+            _ = handleDrop(items, toFolder: folder.id)
         }
     }
 

oAI/Views/Screens/ConversationListView.swift

@@ -240,7 +240,7 @@ struct ConversationListView: View {
                                 } header: {
                                     Text("Unfiled")
                                         .dropDestination(for: String.self) { items, _ in
-                                            handleDrop(items, toFolder: nil)
+                                            _ = handleDrop(items, toFolder: nil)
                                         }
                                 }
                             }
@@ -431,7 +431,7 @@ struct ConversationListView: View {
             }
         }
         .dropDestination(for: String.self) { items, _ in
-            handleDrop(items, toFolder: folder.id)
+            _ = handleDrop(items, toFolder: folder.id)
         }
     }