Overhaul UI with shadcn components and new pages

Add shadcn/ui components (badge, button, card, input, select,
separator). Add company context provider. New pages: Activity,
Approvals, Companies, Costs, Org chart. Restyle existing pages
(Dashboard, Agents, Issues, Goals, Projects) with shadcn components
and dark theme. Update layout, sidebar navigation, and routing.

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

ui/src/api/index.ts

@@ -1,5 +1,10 @@
 export { api } from "./client";
+export { companiesApi } from "./companies";
 export { agentsApi } from "./agents";
 export { projectsApi } from "./projects";
 export { issuesApi } from "./issues";
 export { goalsApi } from "./goals";
+export { approvalsApi } from "./approvals";
+export { costsApi } from "./costs";
+export { activityApi } from "./activity";
+export { dashboardApi } from "./dashboard";