new favourites feature

lib/utils/constants.dart

@@ -51,6 +51,12 @@ abstract final class StorageKeys {
 
   /// How many years ahead Look ahead can navigate (default 5).
   static const lookAheadMaxYears = 'look_ahead_max_years_v1';
+
+  /// Named Overview chart favourites (JSON list).
+  static const overviewFavourites = 'overview_favourites_v1';
+
+  /// Home screen filter widgets (JSON list).
+  static const homeFilterWidgets = 'home_filter_widgets_v1';
 }
 
 /// Named routes registered on [MaterialApp].

lib/utils/tx_filter_metrics.dart

@@ -0,0 +1,87 @@
+/// Apply a [TransactionFilterSelection] and compute Home widget metrics.
+library;
+
+import '../models/bank.dart';
+import '../models/transaction_meta.dart';
+import '../providers/tx_meta_provider.dart';
+import '../utils/tx_calendar.dart';
+import '../widgets/label_filter_dialog.dart';
+
+class TxFilterMetrics {
+  const TxFilterMetrics({
+    required this.count,
+    required this.amountIn,
+    required this.amountOut,
+    required this.transactions,
+  });
+
+  final int count;
+  final double amountIn;
+  final double amountOut;
+  final List<BankTransaction> transactions;
+
+  double get net => amountIn - amountOut;
+}
+
+/// Filter [all] the same way Transactions does (pool → search → flow/amount).
+List<BankTransaction> applyTransactionFilter({
+  required List<BankTransaction> all,
+  required TxMetaController meta,
+  required TransactionFilterSelection filter,
+  DateTime? month,
+}) {
+  final nowMonth = monthStart(month ?? DateTime.now());
+  final pool = filter.monthOnly
+      ? [
+          for (final tx in all)
+            if (_txInMonth(tx, nowMonth)) tx,
+        ]
+      : all;
+
+  return [
+    for (final tx in meta.search(
+      pool,
+      filter.query,
+      labelIds: filter.labelIds,
+    ))
+      if (txMatchesFlow(tx, filter.flow) &&
+          txMatchesAmountRange(tx, filter.amountRange))
+        tx,
+  ];
+}
+
+TxFilterMetrics computeTxFilterMetrics({
+  required List<BankTransaction> all,
+  required TxMetaController meta,
+  required TransactionFilterSelection filter,
+  DateTime? month,
+}) {
+  final filtered = applyTransactionFilter(
+    all: all,
+    meta: meta,
+    filter: filter,
+    month: month,
+  );
+  var amountIn = 0.0;
+  var amountOut = 0.0;
+  for (final tx in filtered) {
+    if (meta.metaFor(tx).internalTransfer) continue;
+    if (tx.amount < 0) {
+      amountOut += tx.amount.abs();
+    } else if (tx.amount > 0) {
+      amountIn += tx.amount;
+    }
+  }
+  return TxFilterMetrics(
+    count: filtered.length,
+    amountIn: amountIn,
+    amountOut: amountOut,
+    transactions: filtered,
+  );
+}
+
+bool _txInMonth(BankTransaction tx, DateTime month) {
+  final date = DateTime.tryParse(tx.date);
+  if (date == null) return false;
+  return isSameMonth(date, month);
+}