refactor: replace cyan accent with ember orange across entire frontend

Swap accent color from cyan (#22d3ee) to ember orange (#f97316) site-wide.
Cyan caused contrast issues and felt generic — orange brings warmth and
urgency fitting for a troubleshooting tool.

Changes:
- CSS variables: accent, accent-hover, accent-dim, accent-text, primary, ring
- Warning color shifted from amber (#fbbf24) to yellow (#eab308) for
  semantic separation from orange accent
- Brand SVGs: logo gradient updated to orange
- 50+ component files: all hardcoded cyan hex values, Tailwind cyan-*
  classes, and rgba(34,211,238,...) glow values replaced
- landing.css: all 45+ cyan references + 5 old border color fixes
- DESIGN-SYSTEM.md bumped to v5 with decisions log
- CLAUDE.md: all color references synced to charcoal palette + orange accent
- PWA theme-color meta tag updated to match sidebar (#10121a)

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

frontend/src/components/dashboard/KnowledgeBaseCards.tsx

@@ -16,7 +16,7 @@ export function KnowledgeBaseCards() {
   const items = [
     { label: 'Flows', value: flowCount, icon: Network, color: '#a78bfa', href: '/trees' },
     { label: 'Scripts', value: '\u2014', icon: Code2, color: '#2dd4bf', href: '/scripts' },
-    { label: 'Pending Review', value: '\u2014', icon: ListChecks, color: '#fbbf24', href: '/review-queue' },
+    { label: 'Pending Review', value: '\u2014', icon: ListChecks, color: '#eab308', href: '/review-queue' },
   ]
 
   return (