Fix release notification resource and add multiple advance reminders

mobile/lib/features/profile/settings_page.dart

@@ -324,17 +324,29 @@ class _SettingsPageState extends State<SettingsPage> {
                     spacing: 6,
                     runSpacing: 7,
                     children: [
-                      for (final minutes in [5, 10, 15, 30, 60])
-                        ChoiceChip(
+                      for (final minutes in AppSettings.allowedReminderMinutes)
+                        FilterChip(
                           label: Text('$minutes 分钟'),
-                          selected: s.reminderMinutes == minutes,
+                          selected: s.reminderOffsets.contains(minutes),
                           onSelected: c.isDemo
                               ? null
-                              : (_) => c.updateSettings(
-                                  (current) => current.copyWith(
-                                    reminderMinutes: minutes,
-                                  ),
-                                ),
+                              : (selected) {
+                                  if (!selected &&
+                                      s.reminderOffsets.length == 1) {
+                                    _notice('请至少保留一个提醒时间');
+                                    return;
+                                  }
+                                  c.updateSettings(
+                                    (current) => current.copyWith(
+                                      reminderOffsets: [
+                                        for (final value
+                                            in current.reminderOffsets)
+                                          if (value != minutes) value,
+                                        if (selected) minutes,
+                                      ],
+                                    ),
+                                  );
+                                },
                         ),
                     ],
                   ),
@@ -345,7 +357,7 @@ class _SettingsPageState extends State<SettingsPage> {
                         : c.reminderResult.status ==
                               ReminderStatus.permissionDenied
                         ? '尚未允许通知权限，点击下方按钮开启。'
-                        : '连续课程只在开始前提醒一次。',
+                        : '可多选提前时间，连续课程按每个选中的时间提醒。',
                     style: TextStyle(
                       fontSize: 11,
                       height: 1.6,