feat(map): add edge-center delta stats, thickness overlay, and layout fix

- Add edge-center sensor pair tables and delta calculations per wafer family.
- Parse and interpolate wafer thickness CSV data for offscreen visualization.
- Refactor ReadoutPanel layout using Item + anchors to fix right-margin clipping.
- Compact E-C Delta text format to fit standard sidebar width.
- Add pytest suite covering delta calculations, layout pairs, and thickness CSV.

src/pygui/backend/visualization/wafer_map_item.py

@@ -38,6 +38,49 @@ from pygui.backend.wafer.zwafer_models import Sensor
 log = logging.getLogger(__name__)
 
 
+def parse_thickness_csv(file_path: str) -> tuple[list[list[float]], str]:
+    """Parse a customer thickness CSV into [x, y, t2] points (mm from center).
+
+    Expected columns (C# parity): Lot Start Time, RC, Site#, Slot#, T2,
+    NGOF, Wafer X, Wafer Y. Only the first wafer (first Slot# value) is read.
+    Returns (points, error) — error is "" on success.
+    """
+    import csv
+
+    points: list[list[float]] = []
+    slot: str | None = None
+    try:
+        with open(file_path, newline="") as fh:
+            reader = csv.reader(fh)
+            header = next(reader, None)
+            if header is None:
+                return [], "Unable to read header row from CSV file."
+            if header and header[-1] == "":  # trailing comma
+                header = header[:-1]
+            nfields = len(header)
+            if nfields != 8:
+                return [], "Incorrect field count in CSV header row."
+            for lno, row in enumerate(reader, start=2):
+                if row and row[-1] == "":
+                    row = row[:-1]
+                if len(row) != nfields:
+                    return [], f"Incorrect field count in CSV row {lno}"
+                if slot is None:
+                    slot = row[3]
+                elif row[3] != slot:
+                    break
+                try:
+                    t2, x, y = float(row[4]), float(row[6]), float(row[7])
+                except ValueError:
+                    return [], f"Malformed value in CSV row {lno}"
+                points.append([x, y, t2])
+    except OSError as exc:
+        return [], f"Unable to read CSV file: {exc}"
+    if not points:
+        return [], "No data found in CSV file."
+    return points, ""
+
+
 def readout_text(values: list[float]) -> str:
     """Full READOUT stats line for the export footer; '' when no data."""
     if not values:
@@ -84,7 +127,7 @@ class WaferMapItem(QQuickPaintedItem):
         self._show_extremes: bool = True
         self._shape: str = "round"
         self._size: float = 300.0
-        self._thickness_data: list[float] = []
+        self._thickness_data: list[list[float]] = []  # [x_mm, y_mm, t2] triples
         self._show_thickness: bool = False
         self._thickness_heatmap:QImage | None = None
         # Hover highlight: index of the marker under the pointer (-1 = none)
@@ -233,13 +276,31 @@ class WaferMapItem(QQuickPaintedItem):
 
     @Property("QVariantList", notify=thicknessChanged)
     def thicknessData(self) -> list:
+        """Thickness measurement points as [x_mm, y_mm, t2] triples."""
         return self._thickness_data
 
     @thicknessData.setter  # type: ignore[no-redef]
     def thicknessData(self, val:list) -> None:
-        self._thickness_data = list(val or [])
+        self._thickness_data = [list(p) for p in (val or [])]
         self._rebuild_thickness()
         self.thicknessChanged.emit()
+        self.update()
+
+    @Property(bool, notify=thicknessChanged)
+    def hasThickness(self) -> bool:
+        return bool(self._thickness_data)
+
+    @Slot(str, result=str)
+    def loadThickness(self, file_path: str) -> str:
+        """Load a customer thickness CSV; returns error message, '' on success."""
+        points, err = parse_thickness_csv(file_path)
+        if err:
+            return err
+        self._thickness_data = points
+        self._rebuild_thickness()
+        self.thicknessChanged.emit()
+        self.update()
+        return ""
         self.update
 
     @Property(bool, notify=showThicknessChanged)
@@ -383,18 +444,14 @@ class WaferMapItem(QQuickPaintedItem):
             painter.drawEllipse(px - ring_r, py - ring_r, 2 * ring_r, 2 * ring_r)
 
     def _rebuild_thickness(self) -> None:
-        """Interpolate thickness data into a gray/orange heatmap QImage."""
-        if not self._sensors or not self._thickness_data:
+        """Interpolate thickness points into a gray/orange heatmap QImage."""
+        if not self._thickness_data:
             self._thickness_heatmap = None
             return
         ds = self._draw_size()
         r_mm = self._wafer_radius_mm()
-        xs = np.array([s.x for s in self._sensors])
-        ys = np.array([s.y for s in self._sensors])
-        vs = np.array(self._thickness_data[:len(self._sensors)], dtype=float)
-        if len(vs) < len(self._sensors):
-            self._thickness_heatmap = None
-            return
+        pts = np.array(self._thickness_data, dtype=float)
+        xs, ys, vs = pts[:, 0], pts[:, 1], pts[:, 2]
         try:
             # No round_clip — see _rebuild_heatmap for why the mask is analytic.
             field = interpolate_field(