fix: convert navigate() calls to Link components for cmd-click support

Replaced button/div onClick + navigate() patterns with React Router
<Link> components so that cmd-click (or ctrl-click) opens pages in a
new browser tab. Changes across:

- AgentDetail: RunListItem, "Issues Touched" items, "Manage" config
  link, "Back to runs" mobile button
- CompanySwitcher: "Company Settings" and "Manage Companies" items
- Approvals: pass detailLink prop instead of onOpen callback
- Org: OrgTree nodes now render as Links

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

ui/src/pages/Approvals.tsx

@@ -117,7 +117,7 @@ export function Approvals() {
               requesterAgent={approval.requestedByAgentId ? (agents ?? []).find((a) => a.id === approval.requestedByAgentId) ?? null : null}
               onApprove={() => approveMutation.mutate(approval.id)}
               onReject={() => rejectMutation.mutate(approval.id)}
-              onOpen={() => navigate(`/approvals/${approval.id}`)}
+              detailLink={`/approvals/${approval.id}`}
               isPending={approveMutation.isPending || rejectMutation.isPending}
             />
           ))}