Offset PE nodes in cube_view to avoid overlapping routers

PE nodes are shifted 1.2mm above (top half) or below (bottom half)
their assigned router position. PE size reduced to 1.4x0.7mm.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/kernbench/topology/builder.py

@@ -946,13 +946,17 @@ def _build_cube_view(spec: dict) -> ViewGraph:
     ) if mesh_data else {}
 
     pe_idx = 0
+    pe_offset_y = 1.2  # mm offset to avoid overlapping router node
     for corner in corners:
+        is_top = corner in ("NW", "NE")
         for ci in range(pe_per_corner):
             pid = f"pe{pe_idx}"
             px, py = corner_pos[corner][ci]
+            # Offset PE above (top) or below (bottom) its router
+            py_view = py - pe_offset_y if is_top else py + pe_offset_y
             nodes[pid] = Node(
                 id=pid, kind="pe", impl="",
-                attrs={"corner": corner}, pos_mm=(px, py),
+                attrs={"corner": corner}, pos_mm=(px, py_view),
                 label=f"PE{pe_idx}",
             )
             pe_idx += 1