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/activity.ts

@@ -0,0 +1,6 @@
+import type { ActivityEvent } from "@paperclip/shared";
+import { api } from "./client";
+
+export const activityApi = {
+  list: (companyId: string) => api.get<ActivityEvent[]>(`/companies/${companyId}/activity`),
+};