feat: full-name tooltips on the glyph count column headers

The sample list's Mount/Gridscan/Screening/Rotation count columns show
only a glyph in the header to save width; hovering now shows the full
name via ToolTipRole. Text headers stay tooltip-free.

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

src/aare/gui/models/user_sample_model.py

@@ -1,4 +1,5 @@
 import re
+from typing import ClassVar
 
 from aarecommon.config.logger import setup_logger
 from aarecommon.models.models import SampleShortInfo, SampleShortInfoList
@@ -235,12 +236,23 @@ class UserSampleSpreadsheet(QAbstractTableModel):
                 [Qt.ItemDataRole.BackgroundRole, Qt.ItemDataRole.ForegroundRole],
             )
 
+    # Hover tooltips for the glyph-only count columns — the icons save header
+    # width but don't explain themselves.
+    HEADER_TOOLTIPS: ClassVar[dict[str, str]] = {
+        "⧂": "Mount count",
+        "▦": "Gridscan count",
+        "⌕": "Screening count",
+        "↻": "Rotation count",
+    }
+
     def headerData(self, section, orientation, role=None):
         if role == Qt.ItemDataRole.DisplayRole:
             if orientation == Qt.Orientation.Horizontal:  # Column header
                 return self.header[section] if self.header else f"Column {section + 1}"
             if orientation == Qt.Orientation.Vertical:  # Row header
                 return str(section + 1)  # Row numbers start from 1
+        if role == Qt.ItemDataRole.ToolTipRole and orientation == Qt.Orientation.Horizontal:
+            return self.HEADER_TOOLTIPS.get(self.header[section])
         return None
 
     def updateCurrentSample(

tests/unit/gui/test_models.py

@@ -304,3 +304,21 @@ def test_spreadsheet_param_columns(status_model):
     model.sort(osc, Qt.SortOrder.AscendingOrder)
     assert model.get_id(0).db_id == 1
     assert model.headerData(hdr.index("Comment"), Qt.Orientation.Horizontal, 0) == "Comment"
+
+
+def test_glyph_count_headers_have_full_name_tooltips(status_model):
+    model = status_model
+    tip = lambda glyph: model.headerData(
+        model.header.index(glyph), Qt.Orientation.Horizontal, Qt.ItemDataRole.ToolTipRole
+    )
+    assert tip("⧂") == "Mount count"
+    assert tip("▦") == "Gridscan count"
+    assert tip("⌕") == "Screening count"
+    assert tip("↻") == "Rotation count"
+    # Text headers explain themselves: no tooltip.
+    assert (
+        model.headerData(
+            model.header.index("Comment"), Qt.Orientation.Horizontal, Qt.ItemDataRole.ToolTipRole
+        )
+        is None
+    )