feat(todo): recurring tasks, set through a picker (ADR 0033, D7)

A task's date may recur: every n days, weeks (on which weekdays),
months (on its day, or its nth or last weekday), years, from its date
or from when it is done, until a day or for n times. Done, it moves on
to the next day after both its date and today, its deadline as far, its
time kept, its done sub-tasks open again and when it was done kept in
its payload; undo writes all of it back. The date sheet offers the rules
that fit the task's day and a rule of the person's own; rows show a
recurring date with its own icon, the task sheet the rule in words.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/todo/halkyon_todo_flutter/lib/l10n/app_localizations.dart

@@ -633,6 +633,156 @@ abstract class AppLocalizations {
   /// In en, this message translates to:
   /// **'Your Inbox comes with the next sync, or once this device holds your account\'s keys.'**
   String get inboxMissingHint;
+
+  /// No description provided for @repeatTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'Repeat'**
+  String get repeatTitle;
+
+  /// No description provided for @repeatNone.
+  ///
+  /// In en, this message translates to:
+  /// **'Doesn\'t repeat'**
+  String get repeatNone;
+
+  /// No description provided for @repeatCustom.
+  ///
+  /// In en, this message translates to:
+  /// **'Custom'**
+  String get repeatCustom;
+
+  /// No description provided for @repeatEveryDay.
+  ///
+  /// In en, this message translates to:
+  /// **'{count, plural, =1{Every day} other{Every {count} days}}'**
+  String repeatEveryDay(int count);
+
+  /// No description provided for @repeatEveryWeek.
+  ///
+  /// In en, this message translates to:
+  /// **'{count, plural, =1{Every week} other{Every {count} weeks}}'**
+  String repeatEveryWeek(int count);
+
+  /// No description provided for @repeatEveryMonth.
+  ///
+  /// In en, this message translates to:
+  /// **'{count, plural, =1{Every month} other{Every {count} months}}'**
+  String repeatEveryMonth(int count);
+
+  /// No description provided for @repeatEveryYear.
+  ///
+  /// In en, this message translates to:
+  /// **'{count, plural, =1{Every year} other{Every {count} years}}'**
+  String repeatEveryYear(int count);
+
+  /// No description provided for @repeatWeekdays.
+  ///
+  /// In en, this message translates to:
+  /// **'Every weekday'**
+  String get repeatWeekdays;
+
+  /// No description provided for @repeatOn.
+  ///
+  /// In en, this message translates to:
+  /// **'{rule} on {on}'**
+  String repeatOn(String rule, String on);
+
+  /// No description provided for @repeatMonthDay.
+  ///
+  /// In en, this message translates to:
+  /// **'day {day}'**
+  String repeatMonthDay(int day);
+
+  /// No description provided for @repeatMonthWeek.
+  ///
+  /// In en, this message translates to:
+  /// **'the {nth, select, 1{first} 2{second} 3{third} 4{fourth} other{last}} {weekday}'**
+  String repeatMonthWeek(String nth, String weekday);
+
+  /// No description provided for @repeatFromCompletion.
+  ///
+  /// In en, this message translates to:
+  /// **'{rule}, from when it\'s done'**
+  String repeatFromCompletion(String rule);
+
+  /// No description provided for @repeatUntil.
+  ///
+  /// In en, this message translates to:
+  /// **'{rule}, until {day}'**
+  String repeatUntil(String rule, String day);
+
+  /// No description provided for @repeatLeft.
+  ///
+  /// In en, this message translates to:
+  /// **'{rule}, {count, plural, =0{this time only} =1{once more} other{{count} more times}}'**
+  String repeatLeft(String rule, int count);
+
+  /// No description provided for @repeatEvery.
+  ///
+  /// In en, this message translates to:
+  /// **'Every'**
+  String get repeatEvery;
+
+  /// No description provided for @repeatUnitDays.
+  ///
+  /// In en, this message translates to:
+  /// **'Days'**
+  String get repeatUnitDays;
+
+  /// No description provided for @repeatUnitWeeks.
+  ///
+  /// In en, this message translates to:
+  /// **'Weeks'**
+  String get repeatUnitWeeks;
+
+  /// No description provided for @repeatUnitMonths.
+  ///
+  /// In en, this message translates to:
+  /// **'Months'**
+  String get repeatUnitMonths;
+
+  /// No description provided for @repeatUnitYears.
+  ///
+  /// In en, this message translates to:
+  /// **'Years'**
+  String get repeatUnitYears;
+
+  /// No description provided for @repeatCountFromCompletion.
+  ///
+  /// In en, this message translates to:
+  /// **'Count from when it\'s done'**
+  String get repeatCountFromCompletion;
+
+  /// No description provided for @repeatCountFromCompletionHint.
+  ///
+  /// In en, this message translates to:
+  /// **'Not from its date: done late, it comes again as long after.'**
+  String get repeatCountFromCompletionHint;
+
+  /// No description provided for @repeatEnds.
+  ///
+  /// In en, this message translates to:
+  /// **'Ends'**
+  String get repeatEnds;
+
+  /// No description provided for @repeatEndsNever.
+  ///
+  /// In en, this message translates to:
+  /// **'Never'**
+  String get repeatEndsNever;
+
+  /// No description provided for @repeatEndsOn.
+  ///
+  /// In en, this message translates to:
+  /// **'On a day'**
+  String get repeatEndsOn;
+
+  /// No description provided for @repeatEndsAfter.
+  ///
+  /// In en, this message translates to:
+  /// **'{count, plural, =1{After once} other{After {count} times}}'**
+  String repeatEndsAfter(int count);
 }
 
 class _AppLocalizationsDelegate