feat: dashboard visual overhaul — amber/blue/danger accents, Inter + JetBrains Mono, sharp corners, tighter density

- Tailwind config: semantic color tokens (amber/blue/danger), borderRadius all zero except full, Inter + JetBrains Mono font families
- index.css: Google Fonts imports, sharp scrollbar, scanline card texture, amber-glow utility
- Dashboard.tsx: three-color accent system (amber primary, blue informational, danger alerts), Inter for labels/prose, JetBrains Mono strictly for data values, all rounded corners removed, tighter spacing (p-4 cards, gap-4 grids, space-y-2 lists), underline-style tabs with amber active indicator, band condition dot indicators, source status dots remapped to semantic colors, StatCard supports per-instance value coloring, 36px minimum touch targets on interactive elements

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

dashboard-frontend/src/index.css

@@ -1,3 +1,6 @@
+@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600&display=swap');
+@import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@400;500&display=swap');
+
 @tailwind base;
 @tailwind components;
 @tailwind utilities;
@@ -5,12 +8,12 @@
 body {
   background: #0a0e17;
   margin: 0;
-  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
+  font-family: 'Inter', system-ui, -apple-system, sans-serif;
   -webkit-font-smoothing: antialiased;
   -moz-osx-font-smoothing: grayscale;
 }
 
-/* Custom scrollbar */
+/* Custom scrollbar — sharp, no radius */
 ::-webkit-scrollbar {
   width: 8px;
   height: 8px;
@@ -22,13 +25,29 @@ body {
 
 ::-webkit-scrollbar-thumb {
   background: #2d3a4d;
-  border-radius: 4px;
+  border-radius: 0;
 }
 
 ::-webkit-scrollbar-thumb:hover {
   background: #3b4a5d;
 }
 
+/* Scanline texture on cards */
+.bg-bg-card {
+  background-image: repeating-linear-gradient(
+    0deg,
+    transparent,
+    transparent 2px,
+    rgba(255,255,255,0.008) 2px,
+    rgba(255,255,255,0.008) 3px
+  );
+}
+
+/* Amber glow utility */
+.amber-glow {
+  box-shadow: 0 0 12px rgba(245,158,11,0.25);
+}
+
 /* Data values use JetBrains Mono */
 .font-mono {
   font-family: 'JetBrains Mono', monospace;
@@ -48,7 +67,6 @@ body {
   animation: pulse 2s cubic-bezier(0.4, 0, 0.6, 1) infinite;
 }
 
-
 /* Toast slide-in animation */
 @keyframes slide-in {
   from {