feat(costs): add billing, quota, and budget control plane

ui/src/pages/ApprovalDetail.tsx

@@ -147,6 +147,7 @@ export function ApprovalDetail() {
   const payload = approval.payload as Record<string, unknown>;
   const linkedAgentId = typeof payload.agentId === "string" ? payload.agentId : null;
   const isActionable = approval.status === "pending" || approval.status === "revision_requested";
+  const isBudgetApproval = approval.type === "budget_override_required";
   const TypeIcon = typeIcon[approval.type] ?? defaultTypeIcon;
   const showApprovedBanner = searchParams.get("resolved") === "approved" && approval.status === "approved";
   const primaryLinkedIssue = linkedIssues?.[0] ?? null;
@@ -260,7 +261,7 @@ export function ApprovalDetail() {
           </div>
         )}
         <div className="flex flex-wrap items-center gap-2">
-          {isActionable && (
+          {isActionable && !isBudgetApproval && (
             <>
               <Button
                 size="sm"
@@ -280,6 +281,11 @@ export function ApprovalDetail() {
               </Button>
             </>
           )}
+          {isBudgetApproval && approval.status === "pending" && (
+            <p className="text-sm text-muted-foreground">
+              Resolve this budget stop from the budget controls on <Link to="/costs" className="underline underline-offset-2">/costs</Link>.
+            </p>
+          )}
           {approval.status === "pending" && (
             <Button
               size="sm"