feat: add RouteFlow component and replace tabbed exchange detail with stacked layout

Replace the 4-tab DetailPanel (Overview/Processors/Exchange/Error) with a
single scrollable view: overview, errors (limited to 1 with +N indicator),
route flow diagram, and processor timeline. DetailPanel now supports
children as an alternative to tabs.

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

src/pages/Inventory/Inventory.tsx

@@ -68,6 +68,7 @@ const NAV_SECTIONS = [
       { label: 'MultiSelect', href: '#multi-select' },
       { label: 'Popover', href: '#popover' },
       { label: 'ProcessorTimeline', href: '#processortimeline' },
+      { label: 'RouteFlow', href: '#routeflow' },
       { label: 'SegmentedTabs', href: '#segmented-tabs' },
       { label: 'ShortcutsBar', href: '#shortcutsbar' },
       { label: 'Tabs', href: '#tabs' },