fix(app): подписи осей и легенда графика стоимости

Крайние подписи оси Y (414.6K поверх 400K) скрыты, числа в русской краткой форме, подписи оси X не обрезаются справа. Добавлена легенда: сплошная линия — стоимость, пунктир — вложено нетто.

app/lib/core/utils/compact_number.dart

@@ -0,0 +1,18 @@
+/// «12,3 тыс», «1,2 млн» — for axis labels and cells too narrow for a full amount.
+///
+/// fl_chart's own short form («414.6K») is English and rounds a step of 50 000 to the same
+/// label twice; this one keeps the Russian suffixes and one decimal below a hundred.
+String compactNumber(double value) {
+  final n = value.abs();
+  String scaled(double x, String suffix) {
+    final s = x >= 100
+        ? x.round().toString()
+        : x.toStringAsFixed(1).replaceAll(RegExp(r'\.0$'), '');
+    return '${s.replaceAll('.', ',')} $suffix';
+  }
+
+  final sign = value < 0 ? '−' : '';
+  if (n >= 1e6) return '$sign${scaled(n / 1e6, 'млн')}';
+  if (n >= 1e3) return '$sign${scaled(n / 1e3, 'тыс')}';
+  return '$sign${n.round()}';
+}

app/lib/features/portfolio/holdings_tab.dart

@@ -5,6 +5,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../../core/theme/chart_colors.dart';
+import '../../core/utils/compact_number.dart';
 import '../../core/utils/ru_date.dart';
 import '../../core/widgets/async_value_view.dart';
 import '../../core/widgets/empty_state.dart';
@@ -249,7 +250,8 @@ class _ValueChart extends StatelessWidget {
       spots.add(FlSpot(i.toDouble(), _d(rows[i].totalRub)));
       invested.add(FlSpot(i.toDouble(), _d(rows[i].investedNetRub)));
     }
-    return SizedBox(
+    const names = ['Стоимость', 'Вложено (нетто)'];
+    final chart = SizedBox(
       height: 220,
       child: LineChart(
         LineChartData(
@@ -258,20 +260,47 @@ class _ValueChart extends StatelessWidget {
           titlesData: FlTitlesData(
             topTitles: const AxisTitles(),
             rightTitles: const AxisTitles(),
-            leftTitles: const AxisTitles(
-              sideTitles: SideTitles(showTitles: true, reservedSize: 56),
+            leftTitles: AxisTitles(
+              sideTitles: SideTitles(
+                showTitles: true,
+                reservedSize: 56,
+                getTitlesWidget: (value, meta) {
+                  // the axis ends sit on the data's min/max and land on top of the round
+                  // labels next to them (414,6 тыс over 400 тыс)
+                  if (value == meta.min || value == meta.max) {
+                    return const SizedBox.shrink();
+                  }
+                  return SideTitleWidget(
+                    axisSide: meta.axisSide,
+                    child: Text(
+                      compactNumber(value),
+                      style: theme.textTheme.bodySmall,
+                    ),
+                  );
+                },
+              ),
             ),
             bottomTitles: AxisTitles(
               sideTitles: SideTitles(
                 showTitles: true,
                 reservedSize: 28,
-                interval: (rows.length / 4).clamp(1, double.infinity),
+                // ticks at the quarters of the span, so the last one is the last day
+                interval: ((rows.length - 1) / 4).clamp(1.0, double.infinity),
                 getTitlesWidget: (value, meta) {
+                  // float steps can land a label a hair before the last one; keep only one
+                  if (value != meta.max &&
+                      meta.max - value < meta.appliedInterval * 0.1) {
+                    return const SizedBox.shrink();
+                  }
                   final i = value.round();
                   if (i < 0 || i >= rows.length) return const SizedBox.shrink();
-                  return Text(
-                    ruMonthYearShort(rows[i].d),
-                    style: theme.textTheme.bodySmall,
+                  return SideTitleWidget(
+                    axisSide: meta.axisSide,
+                    fitInside: SideTitleFitInsideData.fromTitleMeta(meta),
+                    child: Text(
+                      ruMonthYearShort(rows[i].d),
+                      style: theme.textTheme.bodySmall,
+                    ),
                   );
                 },
               ),
@@ -297,9 +326,10 @@ class _ValueChart extends StatelessWidget {
           lineTouchData: LineTouchData(
             touchTooltipData: LineTouchTooltipData(
               getTooltipItems: (touched) => [
-                for (final t in touched)
+                for (final (i, t) in touched.indexed)
                   LineTooltipItem(
-                    '${ruDate(rows[t.x.round()].d)}\n'
+                    '${i == 0 ? '${ruDate(rows[t.x.round()].d)}\n' : ''}'
+                    '${names[t.barIndex]}: '
                     '${MoneyText.format(t.y.toStringAsFixed(2), 'RUB')}',
                     theme.textTheme.bodySmall ?? const TextStyle(),
                   ),
@@ -309,6 +339,43 @@ class _ValueChart extends StatelessWidget {
         ),
       ),
     );
+
+    // the dashed line has no other explanation: say what each of the two is
+    Widget key(Color color, String label, {bool dashed = false}) => Row(
+      mainAxisSize: MainAxisSize.min,
+      children: [
+        SizedBox(
+          width: 18,
+          child: dashed
+              ? Row(
+                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                  children: [
+                    for (var i = 0; i < 3; i++)
+                      Container(width: 4, height: 2, color: color),
+                  ],
+                )
+              : Container(height: 2, color: color),
+        ),
+        const SizedBox(width: 6),
+        Text(label, style: theme.textTheme.bodySmall),
+      ],
+    );
+
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: [
+        chart,
+        const SizedBox(height: 8),
+        Wrap(
+          spacing: 16,
+          runSpacing: 4,
+          children: [
+            key(ChartColors.slot1Blue, names[0]),
+            key(ChartColors.slot4Yellow, names[1], dashed: true),
+          ],
+        ),
+      ],
+    );
   }
 }