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/hooks/useAgents.ts

@@ -0,0 +1,8 @@
+import { useCallback } from "react";
+import { agentsApi } from "../api/agents";
+import { useApi } from "./useApi";
+
+export function useAgents() {
+  const fetcher = useCallback(() => agentsApi.list(), []);
+  return useApi(fetcher);
+}

ui/src/hooks/useApi.ts

@@ -0,0 +1,21 @@
+import { useState, useEffect, useCallback } from "react";
+
+export function useApi<T>(fetcher: () => Promise<T>) {
+  const [data, setData] = useState<T | null>(null);
+  const [error, setError] = useState<Error | null>(null);
+  const [loading, setLoading] = useState(true);
+
+  const load = useCallback(() => {
+    setLoading(true);
+    fetcher()
+      .then(setData)
+      .catch(setError)
+      .finally(() => setLoading(false));
+  }, [fetcher]);
+
+  useEffect(() => {
+    load();
+  }, [load]);
+
+  return { data, error, loading, reload: load };
+}