feat: clicking the '#' header selects all rows

The status column holds no sortable data, so its header click slot
was free: it now does Ctrl+A, pairing with the Unmeasured chip to
grab everything still to be done in one motion. The sort indicator
is put back afterwards - the click drags it onto '#' even though
the model ignores sorting there.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/aare/gui/panels/tell_sample_panel.py

@@ -237,6 +237,16 @@ class TellSamplePanel(QFrame):
         # handler only uses the row, which both views share).
         self.table_view.frozen.setContextMenuPolicy(Qt.ContextMenuPolicy.CustomContextMenu)
         self.table_view.frozen.customContextMenuRequested.connect(self.context_menu)
+        # "#" holds no sortable data; clicking its header selects all rows
+        # instead (Ctrl+A) — the quick way to act on everything visible.
+        # The frozen overlay owns the visible "#" header (not sorting-enabled,
+        # so its sections need explicit clickability); the main header is
+        # connected too in case the overlay is ever dropped.
+        self.table_view.frozen.horizontalHeader().setSectionsClickable(True)
+        self.table_view.frozen.horizontalHeader().sectionClicked.connect(
+            self._select_all_from_status_header
+        )
+        header.sectionClicked.connect(self._select_all_from_status_header)
 
         header.setContextMenuPolicy(Qt.ContextMenuPolicy.CustomContextMenu)
         header.customContextMenuRequested.connect(self.header_context_menu)
@@ -292,6 +302,17 @@ class TellSamplePanel(QFrame):
                 chip.setChecked(True)
                 return
 
+    @Slot(int)
+    def _select_all_from_status_header(self, section: int) -> None:
+        if section != COL_STATUS:
+            return
+        self.table_view.selectAll()
+        # The click also dragged the sort indicator onto "#" (the model
+        # ignores sorting there) — put it back where the data actually is.
+        self.table_view.horizontalHeader().setSortIndicator(
+            self.table_model._sort_col, self.table_model._sort_order
+        )
+
     def _selected_samples(self, clicked_row: int) -> list[SampleShortInfo]:
         """Selected rows if the clicked row is part of the selection, else
         just the clicked row — so right-click on an unselected row acts on it."""

tests/unit/gui/test_tell_sample_panel.py

@@ -124,6 +124,16 @@ def test_queue_drop_chip_accepts_sample_payloads(panel, qtbot, samples):
         chip.dropEvent(drop(bad))
 
 
+def test_status_header_click_selects_all(panel):
+    header = panel.table_view.frozen.horizontalHeader()
+    header.sectionClicked.emit(0)
+    assert len(panel.table_view.selectionModel().selectedRows()) == 3
+    # Other sections keep their normal sort-click behavior.
+    panel.table_view.clearSelection()
+    header.sectionClicked.emit(1)
+    assert len(panel.table_view.selectionModel().selectedRows()) == 0
+
+
 def test_selected_samples_follow_the_click(panel):
     view = panel.table_view
     view.selectRow(0)