feat: replace hardcoded orange hex values with blue equivalents

BrandLogo gradient, EmptyStateIllustrations SVGs, categoryColors,
landing page, brand SVG assets, and all remaining files.
Warning #eab308 → #fbbf24 (amber). categoryColors deduped.

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

frontend/src/components/analytics/FlowAnalyticsPanel.tsx

@@ -16,7 +16,7 @@ import type { FlowAnalyticsResponse, AnalyticsPeriod } from '@/types'
 const CHART_COLORS = {
   resolved: '#34d399',
   escalated: '#f87171',
-  workaround: '#eab308',
+  workaround: '#fbbf24',
   unresolved: '#94a3b8',
 }