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>

kernbench

@@ -0,0 +1,6 @@
+#!/usr/bin/env python
+"""KernBench CLI entry point — run from project root."""
+import sys
+from kernbench.cli.main import main
+
+sys.exit(main())