sam panel: add Clear button for the output log

Run and Clear sit in a horizontal row (Run expands, Clear fixed) so Clear
costs no extra vertical space. Clear calls the existing clearOutput().

src/plugin/sampanel.cpp

@@ -6,6 +6,7 @@
 #include <KLocalizedString>
 
 #include <QFontDatabase>
+#include <QHBoxLayout>
 #include <QKeyEvent>
 #include <QPlainTextEdit>
 #include <QPushButton>
@@ -67,7 +68,18 @@ SamPanel::SamPanel(QWidget *parent)
     m_runButton->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed);
     connect(m_runButton, &QPushButton::clicked, this,
             [this]() { Q_EMIT runRequested(program()); });
-    layout->addWidget(m_runButton);
+
+    m_clearButton = new QPushButton(i18n("Clear"), this);
+    m_clearButton->setMinimumHeight(28);
+    m_clearButton->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
+    connect(m_clearButton, &QPushButton::clicked, this, [this]() { clearOutput(); });
+
+    auto *buttonRow = new QHBoxLayout();
+    buttonRow->setContentsMargins(0, 0, 0, 0);
+    buttonRow->setSpacing(4);
+    buttonRow->addWidget(m_runButton);
+    buttonRow->addWidget(m_clearButton);
+    layout->addLayout(buttonRow);
 
     m_output = new QTextEdit(this);
     m_output->setReadOnly(true);

src/plugin/sampanel.h

@@ -43,6 +43,7 @@ Q_SIGNALS:
 private:
     QPlainTextEdit *m_editor = nullptr;
     QPushButton *m_runButton = nullptr;
+    QPushButton *m_clearButton = nullptr;
     QTextEdit *m_output = nullptr;
 };