Cube-view: increase 45° stub length and component gap for visibility

Stub length increased to 12px (PE/HBM) and 10px (UCIe).
Gap between router and component increased to 30px so both
45° stubs (router end + component end) are clearly visible.

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

src/kernbench/topology/visualizer.py

@@ -607,21 +607,22 @@ def _render_cube_view_svg(view: ViewGraph, spec: dict) -> str:
             # Use left/right offset for multiple blocks on same router
             offset_x = (bi - (len(blocks) - 1) / 2) * (blk_w + 4)
 
+            gap = 30  # px gap between router and component (room for 2 × 45° stubs)
             if kind == "mcpu":
                 # M_CPU: place above (north of) router
                 bx = px - blk_w / 2
-                by = py - r_size - blk_h - 8
+                by = py - r_size - blk_h - gap
             elif kind == "sram":
                 # SRAM: place below (south of) router
                 bx = px - blk_w / 2
-                by = py + r_size + 8
+                by = py + r_size + gap
             else:
                 # PE: place above (top half) or below (bottom half)
                 bx = px + offset_x - blk_w / 2
                 if is_top:
-                    by = py - r_size - blk_h - 4 - bi * (blk_h + 2)
+                    by = py - r_size - blk_h - gap - bi * (blk_h + 2)
                 else:
-                    by = py + r_size + 4 + bi * (blk_h + 2)
+                    by = py + r_size + gap + bi * (blk_h + 2)
 
             # Block rect
             parts.append(
@@ -638,7 +639,7 @@ def _render_cube_view_svg(view: ViewGraph, spec: dict) -> str:
             )
             # Connector: router ─45°─ straight ─45°─ component
             sc = style["stroke"]
-            d = 6  # 45° stub length (px)
+            d = 12  # 45° stub length (px)
             if kind == "mcpu":
                 # Router top → 45° NW stub → vertical → 45° into block bottom
                 rx2, ry2 = px, py - r_size
@@ -705,7 +706,7 @@ def _render_cube_view_svg(view: ViewGraph, spec: dict) -> str:
         tgx, tgy = _pe_hbm_targets[pe_id]
         r_edge_y = rpy + r_size if rpy < hbm_y else rpy - r_size
         # 45° stub from router → vertical → 45° into HBM port
-        d = 8  # stub length
+        d = 12  # stub length
         sx = tgx - rpx
         sd = d if sx >= 0 else -d
         if rpy < hbm_y:
@@ -819,7 +820,7 @@ def _render_cube_view_svg(view: ViewGraph, spec: dict) -> str:
 
             # Connector: router ─45°stub─ straight ─45°stub─ UCIe port
             rpx, rpy = mm2px(crx, cry)
-            d = 6
+            d = 10
             if direction == "N":
                 rx, ry = rpx, rpy - r_size
                 tx, ty = lx, cy_box + ch