feat(visualization): extract ring_boundaries to radial_metrics

- add radial_metrics: ring_boundaries + bucket_by_ring
- replace WaferMapItem inline logic with ring_boundaries()
- fix outer boundary: sensor max-hypot*1.05 (was wafer_radius_mm)
- add LicenseModel.reviewAccessBlocked() (ADR-0005 deferred)
- add appendActivityLog test
- add test_radial_metrics.py (89 lines, full edge-case coverage)
- update README: licmgr --level flag + date format

src/pygui/backend/visualization/radial_metrics.py

@@ -0,0 +1,38 @@
+from __future__ import annotations
+
+import math
+
+from pygui.backend.wafer.zwafer_models import Sensor
+
+
+def ring_boundaries(sensors: list[Sensor]) -> list[float]:
+    """Distinct radial distances of sensor groups, sorted ascending, plus the outer boundary."""
+    if not sensors:
+        r = 150.0
+        return [r * f for f in (0.25, 0.50, 0.75, 1.0)]
+    # Cluster radii that are within 2 mm of each other into one ring; skip center point.
+    radii = sorted(r for r in {math.hypot(s.x, s.y) for s in sensors} if r > 1.0)
+    groups: list[float] = []
+    for r in radii:
+        if not groups or r - groups[-1] > 2.0:
+            groups.append(r)
+        else:
+            groups[-1] = (groups[-1] + r) / 2  # merge close values
+    # Always include the outer boundary ring so the wafer circle is drawn.
+    outer = max(math.hypot(s.x, s.y) for s in sensors) * 1.05
+    if not groups or outer - groups[-1] > 2.0:
+        groups.append(outer)
+    return groups
+
+
+def bucket_by_ring(sensors: list[Sensor], values: list[float]) -> dict[int, list[float]]:
+    """Group each sensor's value under the index of its nearest ring boundary."""
+    boundaries = ring_boundaries(sensors)
+    result: dict[int, list[float]] = {i: [] for i in range(len(boundaries))}
+    for i, s in enumerate(sensors):
+        if i >= len(values):
+            continue
+        r = math.hypot(s.x, s.y)
+        idx = min(range(len(boundaries)), key=lambda j: abs(boundaries[j] - r))
+        result[idx].append(values[i])
+    return result

src/pygui/backend/visualization/wafer_map_item.py

@@ -28,6 +28,7 @@ from PySide6.QtQml import QmlElement
 from PySide6.QtQuick import QQuickPaintedItem
 
 from pygui.backend.models.frame_stats import compute_stats
+from pygui.backend.visualization.radial_metrics import ring_boundaries
 from pygui.backend.visualization.rbf_heatmap import (
     ellipse_alpha,
     interpolate_field,
@@ -517,22 +518,7 @@ class WaferMapItem(QQuickPaintedItem):
 
     def _sensor_ring_radii_mm(self) -> list[float]:
         """Distinct radial distances of sensor groups, sorted ascending, plus the outer boundary."""
-        if not self._sensors:
-            r = self._wafer_radius_mm()
-            return [r * f for f in (0.25, 0.50, 0.75, 1.0)]
-        # Cluster radii that are within 2 mm of each other into one ring; skip center point.
-        radii = sorted(r for r in {math.hypot(s.x, s.y) for s in self._sensors} if r > 1.0)
-        groups: list[float] = []
-        for r in radii:
-            if not groups or r - groups[-1] > 2.0:
-                groups.append(r)
-            else:
-                groups[-1] = (groups[-1] + r) / 2  # merge close values
-        # Always include the outer boundary ring so the wafer circle is drawn.
-        outer = self._wafer_radius_mm()
-        if not groups or outer - groups[-1] > 2.0:
-            groups.append(outer)
-        return groups
+        return ring_boundaries(self._sensors)
 
     def _scale(self, ds: int, r_mm: float) -> float:
         """Pixels per mm. The wafer radius maps to ds//2 - 24 px."""