feat: group transactions by date inside month accordions

Add two-layer grouping to the shared transaction list: each month
accordion now renders one card per occurred_at date (most recent first)
with a date label and txn count header, nesting the usual transaction
rows inside. Add dateLabel + groupByDate helpers to src/common and use
them in TransactionList. Month accordions, scroll pill/menu, and month
totals are unchanged.

src/common/components/TransactionList.tsx

@@ -14,7 +14,7 @@ import ExpandMoreIcon from "@mui/icons-material/ExpandMore";
 import KeyboardArrowDownIcon from "@mui/icons-material/KeyboardArrowDown";
 import { formatCurrency } from "../../../react-openapi";
 import type { ExpenseItem, TxnFieldConfigs } from "../types";
-import { groupByMonth } from "../utils/transactions";
+import { groupByDate, groupByMonth } from "../utils/transactions";
 import { monthLabel } from "../utils/dates";
 import { TransactionRow } from "./TransactionRow";
 
@@ -160,13 +160,48 @@ export function TransactionList({ items, fields }: TransactionListProps) {
               </AccordionSummary>
               <AccordionDetails sx={{ p: 1.5, pt: 1 }}>
                 <Box sx={{ display: "flex", flexDirection: "column", gap: 1 }}>
-                  {group.items.map((item) => (
-                    <TransactionRow
-                      key={item.id}
-                      item={item}
-                      currency={group.currency}
-                      fields={fields}
-                    />
+                  {groupByDate(group.items).map((dateGroup) => (
+                    <Box
+                      key={dateGroup.date}
+                      sx={{
+                        border: "1px solid",
+                        borderColor: "divider",
+                        borderRadius: 2,
+                        backgroundColor: "background.default",
+                        p: 1,
+                      }}
+                    >
+                      <Box
+                        sx={{
+                          display: "flex",
+                          alignItems: "center",
+                          gap: 1,
+                          px: 1,
+                          pb: 1,
+                          borderBottom: "1px solid",
+                          borderColor: "divider",
+                          mb: 1,
+                        }}
+                      >
+                        <Typography variant="subtitle2" fontWeight={600} sx={{ letterSpacing: "-0.01em" }}>
+                          {dateGroup.label}
+                        </Typography>
+                        <Box sx={{ flex: 1 }} />
+                        <Typography variant="caption" color="text.secondary">
+                          {dateGroup.items.length} transaction{dateGroup.items.length === 1 ? "" : "s"}
+                        </Typography>
+                      </Box>
+                      <Box sx={{ display: "flex", flexDirection: "column", gap: 1 }}>
+                        {dateGroup.items.map((item) => (
+                          <TransactionRow
+                            key={item.id}
+                            item={item}
+                            currency={group.currency}
+                            fields={fields}
+                          />
+                        ))}
+                      </Box>
+                    </Box>
                   ))}
                 </Box>
               </AccordionDetails>

src/common/utils/dates.ts

@@ -63,4 +63,9 @@ export function monthLabel(key: string): string {
   if (!y || !m) return key;
   const d = new Date(y, m - 1, 1);
   return d.toLocaleDateString("en-IN", { month: "long", year: "numeric" });
+}
+
+export function dateLabel(value: string): string {
+  const d = parseOccurredAt(value);
+  return d.toLocaleDateString("en-IN", { day: "numeric", month: "short", year: "numeric" });
 }

src/common/utils/transactions.ts

@@ -1,10 +1,34 @@
 import type { ExpenseItem, GroupedMonth } from "../types";
-import { monthKey, parseOccurredAt } from "./dates";
+import { dateLabel, monthKey, parseOccurredAt } from "./dates";
 
 export function isExpense(item: ExpenseItem): boolean {
   return (item.amount ?? 0) < 0;
 }
 
+export interface DateGroup {
+  date: string;
+  label: string;
+  items: ExpenseItem[];
+}
+
+export function groupByDate(items: ExpenseItem[]): DateGroup[] {
+  const sorted = [...items].sort(
+    (a, b) => parseOccurredAt(b.occurred_at).getTime() - parseOccurredAt(a.occurred_at).getTime(),
+  );
+  const map = new Map<string, ExpenseItem[]>();
+  for (const item of sorted) {
+    const key = item.occurred_at ?? "";
+    const list = map.get(key) ?? [];
+    list.push(item);
+    map.set(key, list);
+  }
+  return [...map.entries()].map(([date, list]) => ({
+    date,
+    label: dateLabel(date),
+    items: list,
+  }));
+}
+
 export function groupByMonth(items: ExpenseItem[]): GroupedMonth[] {
   const map = new Map<string, ExpenseItem[]>();
   for (const item of items) {