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/flowpilot/FlowPilotSession.tsx

@@ -118,7 +118,7 @@ export function FlowPilotSession({
             <div className="mb-4">
               <button
                 onClick={() => setShowShareCommunication(true)}
-                className="flex items-center gap-2 rounded-lg bg-cyan-500/10 border border-cyan-500/20 px-4 py-2.5 text-sm font-medium text-cyan-400 hover:bg-cyan-500/20 transition-colors"
+                className="flex items-center gap-2 rounded-lg bg-orange-500/10 border border-orange-500/20 px-4 py-2.5 text-sm font-medium text-orange-400 hover:bg-orange-500/20 transition-colors"
               >
                 <FileText size={16} />
                 {shareLabel}