Document LmxProxy protocol in DCL, strengthen plan generation traceability guards, and add UI constraints

- Replace "custom protocol" placeholder with full LmxProxy details (gRPC transport, SDK API mapping, session management, keep-alive, TLS, batch ops)
- Add bullet-level requirement traceability, design constraint traceability (52 KDD + 6 CD), split-section tracking, and post-generation orphan check to plan framework
- Resolve Q9 (LmxProxy), Q11 (REST test server), Q13 (solo dev), Q14 (self-test), Q15 (Machine Data DB out of scope)
- Set Central UI constraints: Blazor Server + Bootstrap only, no heavy frameworks, custom components, clean corporate design

CLAUDE.md

@@ -119,7 +119,9 @@ There is no source code in this project — only design documentation in markdow
 - Automatic dual-node recovery from persistent storage.
 
 ### UI & Monitoring
-- Central UI: Blazor Server (ASP.NET Core + SignalR). Real-time push for debug view, health dashboard, deployment status.
+- Central UI: Blazor Server (ASP.NET Core + SignalR) with Bootstrap CSS. No third-party component frameworks (no Blazorise, MudBlazor, Radzen, etc.). Build custom Blazor components for tables, grids, forms, etc.
+- UI design: Clean, corporate, internal-use aesthetic. Not flashy. Use the `frontend-design` skill when designing UI pages/components.
+- Real-time push for debug view, health dashboard, deployment status.
 - Health reports: 30s interval, 60s offline threshold, monotonic sequence numbers, raw error counts per interval.
 - Dead letter monitoring as a health metric.
 - Site Event Logging: 30-day retention, 1GB storage cap, daily purge, paginated queries with keyword search.