Add React UI with Vite

Dashboard, agents, goals, issues, and projects pages with sidebar
navigation. API client layer, custom hooks, and shared layout
components. Built with Vite and TypeScript.

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

ui/src/lib/utils.ts

@@ -0,0 +1,15 @@
+export function cn(...classes: (string | false | null | undefined)[]) {
+  return classes.filter(Boolean).join(" ");
+}
+
+export function formatCents(cents: number): string {
+  return `$${(cents / 100).toFixed(2)}`;
+}
+
+export function formatDate(date: Date | string): string {
+  return new Date(date).toLocaleDateString("en-US", {
+    month: "short",
+    day: "numeric",
+    year: "numeric",
+  });
+}