Initial implementation of NetWatch network latency monitor

SPA for real-time latency monitoring to 10 internet hosts:
- 250ms update interval with 300s history sparkline graphs
- Color-coded latency display (green <50ms to red >500ms)
- HEAD request timing with no-cors mode for cross-origin support
- Built with Vite + Tailwind CSS v4, all dependencies bundled
- Designed for static bucket deployment

src/styles.css

@@ -0,0 +1,18 @@
+@import "tailwindcss";
+
+@theme {
+  --color-latency-excellent: #22c55e;
+  --color-latency-good: #84cc16;
+  --color-latency-moderate: #eab308;
+  --color-latency-poor: #f97316;
+  --color-latency-bad: #ef4444;
+  --color-latency-offline: #6b7280;
+}
+
+body {
+  font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
+}
+
+.sparkline-container {
+  background: linear-gradient(to bottom, rgba(255,255,255,0.02) 0%, rgba(255,255,255,0) 100%);
+}