fix(todo): unify details panel button styles

- Add/Edit, Save, and Cancel buttons now use consistent primary color
- Hide Add/Edit button when in details edit mode
- Fix text colors for proper visibility

Author: lonerOrz

todo/Panel.qml

@@ -1189,10 +1189,10 @@ Item {
               NButton {
                 text: detailDialog.todoDetails.length > 0 ? pluginApi?.tr("panel.todo_details.button_edit_details") : pluginApi?.tr("panel.todo_details.button_add_details")
                 icon: "pencil"
-                backgroundColor: Color.mSurfaceVariant
-                textColor: Color.mOnSurface
+                backgroundColor: Color.mPrimary
+                textColor: Color.mOnPrimary
                 fontSize: Style.fontSizeS
-                outlined: true
+                visible: !detailsEditMode
                 onClicked: {
                   detailsEditMode = true;
                   Qt.callLater(function () {
@@ -1240,6 +1240,7 @@ Item {
               NButton {
                 text: pluginApi?.tr("panel.todo_details.button_save")
                 backgroundColor: Color.mPrimary
+                textColor: Color.mOnPrimary
                 onClicked: {
                   updateTodo(detailDialog.todoId, {
                                details: detailsTextArea.text
@@ -1251,7 +1252,8 @@ Item {
 
               NButton {
                 text: pluginApi?.tr("panel.todo_details.button_cancel")
-                backgroundColor: Color.mSurfaceVariant
+                backgroundColor: Color.mPrimary
+                textColor: Color.mOnPrimary
                 onClicked: {
                   detailsEditMode = false;
                 }