Remove xbar/noc remnants, rule-based cube-view connectors

- Delete xbar.py and noc.py (TwoDMeshNocComponent) — unused since router mesh
- Remove xbar_v1/noc_2d_mesh_v1 from components.yaml
- Fix pe_to_xbar → pe_to_router in routing exclusion set
- Fix xbar_to_hbm_bw_gbs → hbm_to_router_bw_gbs in report.py
- Update all docstrings/comments referencing xbar/bridge → router mesh
- Cube-view connectors: rule-based _connector_points helper
  - PE↔router: single diagonal line (not chevron)
  - UCIe N/S: 45°→horizontal→45°
  - UCIe E/W: 45°→vertical→45°
  - HBM ports: 45°→horizontal→45°

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

topology.yaml

@@ -55,7 +55,7 @@ cube:
     ucie_mm: { size: 2.0 }
 
   pe_layout:
-    corners: [NW, NE, SW, SE]   # N corners → xbar top row; S corners → xbar bottom row
+    corners: [NW, NE, SW, SE]   # N corners → top PE rows; S corners → bottom PE rows
     pe_per_corner: 2             # total PEs per cube: 4 * 2 = 8
 
   pe_template:
@@ -97,7 +97,7 @@ cube:
 
   # Physical placement of non-PE components (mm coordinates)
   placement:
-    m_cpu:  { pos_mm: [7.5, 2.0] }   # top center area, near UCIe-N
+    m_cpu:  { pos_mm: [7.5, 3.0] }   # top center, below UCIe-N
     sram:   { pos_mm: [1.5, 9.0] }   # left side, below HBM zone
 
   ucie: