refactor(bills): migrate BillsPage to React Query (R5.2)

Reuses the shared useBills/useCategories caches (+ new useBillTemplates/
useDeletedBills), so bill mutations here now also refresh the Tracker/badge
live via the shared ['bills'] key. Optimistic list edits (delete, reorder)
write through queryClient.setQueryData; post-mutation load() calls became a
refresh() that invalidates the 4 page queries.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/hooks/useQueries.js

@@ -81,3 +81,19 @@ export function useAnalyticsSummary(params) {
     placeholderData: keepPreviousData,
   });
 }
+
+export function useBillTemplates() {
+  return useQuery({
+    queryKey: ['bill-templates'],
+    queryFn: () => api.billTemplates(),
+    staleTime: 1000 * 60 * 5,
+  });
+}
+
+export function useDeletedBills() {
+  return useQuery({
+    queryKey: ['deleted-bills'],
+    queryFn: () => api.deletedBills().catch(() => []), // non-critical: never block the page
+    staleTime: 1000 * 60 * 5,
+  });
+}

client/pages/BillsPage.jsx

@@ -1,5 +1,7 @@
 import React, { useEffect, useState, useCallback, useMemo, useRef } from 'react';
 import { useSearchParams } from 'react-router-dom';
+import { useQueryClient } from '@tanstack/react-query';
+import { useBills, useCategories, useBillTemplates, useDeletedBills } from '@/hooks/useQueries';
 import { Plus, ChevronRight, SlidersHorizontal, Search, Trash2 } from 'lucide-react';
 import { toast } from 'sonner';
 import { Button } from '@/components/ui/button';
@@ -599,12 +601,28 @@ function HistoryVisibilityDialog({ bill, onClose, onSaved }) {
 // ── Bills Page ─────────────────────────────────────────────────────────────
 export default function BillsPage() {
   const [searchParams] = useSearchParams();
-  const [bills,        setBills]       = useState([]);
-  const [categories,   setCategories]  = useState([]);
-  const [savedTemplates, setSavedTemplates] = useState([]);
-  const [deletedBills, setDeletedBills] = useState([]);
+  const queryClient = useQueryClient();
+  // React Query is the source of truth (reuses the shared ['bills']/['categories']
+  // caches, so bill mutations here also refresh the Tracker/badge). Optimistic
+  // list edits below write to the cache via setQueryData.
+  const { data: bills = [], isPending: billsPending } = useBills();
+  const { data: categories = [] } = useCategories();
+  const { data: savedTemplates = [] } = useBillTemplates();
+  const { data: deletedBills = [] } = useDeletedBills();
+  const loading = billsPending;
+  const setBills = useCallback(
+    (updater) => queryClient.setQueryData(['bills'], prev => (
+      typeof updater === 'function' ? updater(prev || []) : updater
+    )),
+    [queryClient],
+  );
+  const refresh = useCallback(() => Promise.all([
+    queryClient.invalidateQueries({ queryKey: ['bills'] }),
+    queryClient.invalidateQueries({ queryKey: ['categories'] }),
+    queryClient.invalidateQueries({ queryKey: ['bill-templates'] }),
+    queryClient.invalidateQueries({ queryKey: ['deleted-bills'] }),
+  ]), [queryClient]);
   const [showDeleted, setShowDeleted] = useState(false);
-  const [loading,      setLoading]     = useState(true);
   const [showInactive, setShowInactive] = useState(false);
   const [search, setSearch] = useState('');
   const [draggingId, setDraggingId] = useState(null);
@@ -641,26 +659,6 @@ export default function BillsPage() {
     localStorage.setItem(BILLS_SORT_KEY, billsSort);
   }, [billsSort]);
 
-  const load = useCallback(async () => {
-    try {
-      const [billsRes, catRes, templateRes, deletedRes] = await Promise.all([
-        api.allBills(),
-        api.categories(),
-        api.billTemplates(),
-        api.deletedBills().catch(() => []), // non-critical: never block the page
-      ]);
-      setBills(billsRes  || []);
-      setCategories(catRes || []);
-      setSavedTemplates(templateRes || []);
-      setDeletedBills(deletedRes || []);
-    } catch (err) {
-      toast.error(err.message);
-    } finally {
-      setLoading(false);
-    }
-  }, []);
-
-  useEffect(() => { load(); }, [load]);
 
   useEffect(() => {
     const querySearch = searchParams.get('search') || '';
@@ -745,7 +743,7 @@ export default function BillsPage() {
       if (bill.active && reason) payload.inactive_reason = reason;
       await api.updateBill(bill.id, payload);
       toast.success(bill.active ? 'Bill deactivated' : 'Bill activated');
-      load();
+      refresh();
     } catch (err) {
       toast.error(err.message);
     }
@@ -771,7 +769,7 @@ export default function BillsPage() {
             try {
               await api.restoreBill(bill.id);
               toast.success(`"${bill.name}" restored`);
-              load();
+              refresh();
             } catch (err) {
               toast.error(err.message || 'Failed to restore bill');
             }
@@ -780,7 +778,7 @@ export default function BillsPage() {
       });
       setDeleteTarget(null);
       setDeleteConfirmed(false);
-      load();
+      refresh();
     } catch (err) {
       toast.error(err.message || 'Failed to delete bill');
     } finally {
@@ -792,7 +790,7 @@ export default function BillsPage() {
     try {
       await api.restoreBill(bill.id);
       toast.success(`"${bill.name}" restored`);
-      await load();
+      await refresh();
     } catch (err) {
       toast.error(err.message || 'Failed to restore bill');
     }
@@ -850,10 +848,10 @@ export default function BillsPage() {
     try {
       await api.reorderBills(reorderPayload(nextBills));
       toast.success('Bill order saved');
-      load();
+      refresh();
     } catch (err) {
       toast.error(err.message || 'Failed to save bill order');
-      load();
+      refresh();
     } finally {
       setMovingBillId(null);
     }
@@ -1155,7 +1153,7 @@ export default function BillsPage() {
           initialBill={modal.initialBill}
           categories={categories}
           onClose={() => setModal(null)}
-          onSave={load}
+          onSave={refresh}
           onDuplicate={handleDuplicateBill}
         />
       )}
@@ -1164,7 +1162,7 @@ export default function BillsPage() {
         <HistoryVisibilityDialog
           bill={historyTarget}
           onClose={() => setHistoryTarget(null)}
-          onSaved={load}
+          onSaved={refresh}
         />
       )}