Wire PE_MMU to router mesh for MmuMapMsg delivery

Add router → PE_MMU edge so MmuMapMsg can reach PE_MMU via
the router mesh. Unskip all PE_MMU fabric tests.

339 passed, 0 skipped

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

src/kernbench/topology/builder.py

@@ -550,6 +550,14 @@ def _instantiate_cube(
                         distance_mm=clinks.get("noc_to_pe_cpu_mm", 0.0),
                         kind="pe_response",
                     ))
+                # PE_MMU ↔ router (mapping install path)
+                mmu_id = f"{cp}.{pe_prefix}.pe_mmu"
+                if mmu_id in nodes:
+                    edges.append(Edge(
+                        src=rid, dst=mmu_id,
+                        distance_mm=0.0,
+                        kind="command",
+                    ))
             elif item.endswith(".hbm"):
                 pass  # HBM edges handled below (all routers)
             elif item == "m_cpu":