Fix black row text after moving to a folder, remove duplicate chevron

Pin conversation row title text to .foregroundStyle(.primary) instead
of the implicit default — under List's sidebar/source-list style,
AppKit's row highlighting could resolve default text to black on a
just-interacted-with row (e.g. right after a drag/context-menu move),
making it unreadable. Also drop Section(isExpanded:), which was
rendering its own native disclosure chevron on the right in addition
to the custom one already in the header on the left; folder collapse
now works purely off the existing collapsedFolders state with a plain
Section, so only the intended left-side chevron remains.

oAI/Views/Main/SidebarView.swift

@@ -131,10 +131,12 @@ struct SidebarView: View {
                     ForEach(folders) { folder in
                         let folderConversations = conversationsByFolder[folder.id] ?? []
                         if !folderConversations.isEmpty || searchText.isEmpty {
-                            Section(isExpanded: isExpandedBinding(for: folder.id)) {
+                            Section {
+                                if !collapsedFolders.contains(folder.id) {
                                     ForEach(folderConversations) { conversation in
                                         conversationRow(conversation)
                                     }
+                                }
                             } header: {
                                 folderHeader(folder)
                             }
@@ -204,19 +206,6 @@ struct SidebarView: View {
         }
     }
 
-    private func isExpandedBinding(for folderId: UUID) -> Binding<Bool> {
-        Binding(
-            get: { !collapsedFolders.contains(folderId) },
-            set: { isExpanded in
-                if isExpanded {
-                    collapsedFolders.remove(folderId)
-                } else {
-                    collapsedFolders.insert(folderId)
-                }
-            }
-        )
-    }
-
     private func handleDrop(_ items: [String], toFolder folderId: UUID?) -> Bool {
         var moved = false
         for idString in items {
@@ -423,6 +412,7 @@ struct SidebarConversationRow: View {
         VStack(alignment: .leading, spacing: 2) {
             Text(conversation.name)
                 .font(.system(size: 13, weight: .medium))
+                .foregroundStyle(.primary)
                 .lineLimit(1)
             HStack(spacing: 4) {
                 Text("^[\(conversation.messageCount) message](inflect: true)")

oAI/Views/Screens/ConversationListView.swift

@@ -221,10 +221,12 @@ struct ConversationListView: View {
                             ForEach(folders) { folder in
                                 let folderConversations = conversationsByFolder[folder.id] ?? []
                                 if !folderConversations.isEmpty || searchText.isEmpty {
-                                    Section(isExpanded: isExpandedBinding(for: folder.id)) {
+                                    Section {
+                                        if !collapsedFolders.contains(folder.id) {
                                             ForEach(folderConversations) { conversation in
                                                 conversationRow(conversation)
                                             }
+                                        }
                                     } header: {
                                         folderHeader(folder)
                                     }
@@ -443,19 +445,6 @@ struct ConversationListView: View {
         }
     }
 
-    private func isExpandedBinding(for folderId: UUID) -> Binding<Bool> {
-        Binding(
-            get: { !collapsedFolders.contains(folderId) },
-            set: { isExpanded in
-                if isExpanded {
-                    collapsedFolders.remove(folderId)
-                } else {
-                    collapsedFolders.insert(folderId)
-                }
-            }
-        )
-    }
-
     private func handleDrop(_ items: [String], toFolder folderId: UUID?) -> Bool {
         var moved = false
         for idString in items {
@@ -696,6 +685,7 @@ struct ConversationRow: View {
         VStack(alignment: .leading, spacing: 4) {
             Text(conversation.name)
                 .font(.system(size: 15, weight: .semibold))
+                .foregroundStyle(.primary)
                 .lineLimit(1)
 
             HStack(spacing: 6) {