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/approvals.ts

@@ -0,0 +1,15 @@
+import type { Approval } from "@paperclip/shared";
+import { api } from "./client";
+
+export const approvalsApi = {
+  list: (companyId: string, status?: string) =>
+    api.get<Approval[]>(
+      `/companies/${companyId}/approvals${status ? `?status=${encodeURIComponent(status)}` : ""}`,
+    ),
+  create: (companyId: string, data: Record<string, unknown>) =>
+    api.post<Approval>(`/companies/${companyId}/approvals`, data),
+  approve: (id: string, decisionNote?: string) =>
+    api.post<Approval>(`/approvals/${id}/approve`, { decisionNote }),
+  reject: (id: string, decisionNote?: string) =>
+    api.post<Approval>(`/approvals/${id}/reject`, { decisionNote }),
+};