Add detail pages, property panels, and restyle list pages

New pages: AgentDetail, GoalDetail, IssueDetail, ProjectDetail, Inbox,
MyIssues. New feature components: AgentProperties, GoalProperties,
IssueProperties, ProjectProperties, GoalTree, NewIssueDialog. Add
heartbeats API client. Restyle all list pages (Agents, Issues, Goals,
Projects, Dashboard, Costs, Activity, Org) with EntityRow, FilterBar,
and improved layouts. Add routing for detail views.

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

ui/src/api/heartbeats.ts

@@ -0,0 +1,9 @@
+import type { HeartbeatRun } from "@paperclip/shared";
+import { api } from "./client";
+
+export const heartbeatsApi = {
+  list: (companyId: string, agentId?: string) => {
+    const params = agentId ? `?agentId=${agentId}` : "";
+    return api.get<HeartbeatRun[]>(`/companies/${companyId}/heartbeat-runs${params}`);
+  },
+};