feat: bold dashboard redesign with inline stats, section labels, and chip icons

Restructure QuickStartPage for a more professional, informative layout:
- Left-aligned hero greeting (text-4xl) with date context and inline stat strip
- GreetingStatStrip shows resolved/active/MTTR at a glance
- Remove collapsible toggle — dashboard stats always visible
- Section labels with trailing border lines for visual hierarchy
- Suggestion chips with category icons, card-style hover, press feedback
- Fix cyan focus ring and icon color to ember orange design system
- Session cards: line-clamp-2 descriptions, font-medium text, problem_domain metadata
- Widen container max-w-3xl → max-w-4xl for breathing room
- Add .impeccable.md and .github/copilot-instructions.md design context
- CLAUDE.md audit: fix stale references, remove duplication, update counts

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

frontend/src/components/dashboard/PerformanceCards.tsx

@@ -52,7 +52,7 @@ export function PerformanceCards() {
       label: 'Active Now',
       value: active,
       icon: TrendingUp,
-      iconColor: '#38bdf8',
+      iconColor: '#848b9b',
       href: '/sessions?filter=active',
     },
     {