Add web topology viewer with hot path visualization

- FastAPI backend (server.py) with REST API + WebSocket for event streaming
- SVG-based topology viewer (index.html) with SIP/CUBE/PE drill-down views
- Event logging infrastructure (event_log.py) generating events from real
  probe cases (H2D/D2H/PE-DMA) and bench workloads (QKV GEMM single/multi-PE)
- Timeline replay engine with play/pause, speed control, and scrubbing
- Workload selector dropdown grouped by category (Probe/Bench)
- CLI entry points: kernbench web, ./kernbench wrapper scripts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/kernbench/cli/main.py

@@ -28,6 +28,11 @@ def build_parser() -> argparse.ArgumentParser:
     probep.add_argument("--case", default="all", help="Case name or 'all' (default: all)")
     probep.set_defaults(_handler=cmd_probe)
 
+    webp = sub.add_parser("web", help="Launch topology viewer in browser")
+    webp.add_argument("--port", type=int, default=8765, help="HTTP port (default: 8765)")
+    webp.add_argument("--no-open", action="store_true", help="Don't auto-open browser")
+    webp.set_defaults(_handler=cmd_web)
+
     return p
 
 
@@ -36,6 +41,12 @@ def engine_factory(topology: object, device: DeviceSelector) -> SimEngine:
     return GraphEngine(topo_obj)
 
 
+def cmd_web(args) -> int:
+    from kernbench.web.server import serve
+    serve(port=args.port, open_browser=not args.no_open)
+    return 0
+
+
 def cmd_run(args) -> int:
     print("> Running benchmark with:", args)