feat: redesign exchange detail page with interactive processor inspector

- Rewrite ExchangeDetail with split Message IN/OUT panels that update
  on processor click, error panel for failed processors, and
  Timeline/Flow toggle for the processor visualization
- Add correlation chain in header with status-colored clickable nodes
  sorted by start time, labeled "Correlated Exchanges"
- Add Exchange ID column and inspect button (↗) to Dashboard table
- Add "Open full details" link in the exchange slide-in panel
- Add selectedIndex prop to ProcessorTimeline and RouteFlow for
  highlighting the active processor
- Add onNodeClick + selectedIndex to RouteFlow for interactive use
- Add correlationGroup field to exchange mock data
- Fix sidebar section toggle indentation alignment

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

src/design-system/layout/Sidebar/Sidebar.module.css

@@ -214,9 +214,9 @@
 .treeSectionToggle {
   display: flex;
   align-items: center;
-  gap: 6px;
+  gap: 2px;
   width: 100%;
-  padding: 8px 12px 4px;
+  padding: 8px 0 4px;
 }
 
 .treeSectionChevronBtn {