feat(todo): quick add's keys, sub-projects' colours, a task's menu on a right click, and the completed tasks deleted at once

The developer's list of 9 Nov 2026, Todo's part:

- Quick add: the down arrow and Tab move into the description, with its
  cursor (halkyon_editor's fix); Escape closes the projects or labels
  suggested first, then closes quick add, what was typed discarded; the
  project's chip shows the project's colour.
- A project without a colour of its own shows its parent's, the nearest
  ancestor's with one (colorOfProject, TodoCubit.colorOf), wherever a
  project's colour shows; the project editor's "Same colour as its parent"
  keeps it so, and the parent picker shows each project in its colour. A
  project of its own always has one.
- The task pane's x closes it, always; Close left the ⋮ menu.
- A task's row opens its menu on a right click: Mark as done, Date, Move
  to, Labels, Priority, Deadline, Duplicate and Delete, the selection's
  actions for that one task.
- Delete completed tasks, in the ⋮ of the Inbox, Today, Upcoming and a
  project, with Undo: the tasks leave the list at once and are deleted
  once the snack bar goes without its Undo (halkyon_ui's showUndoSnackBar
  gains onKept).

Whats-New: Quick add: the arrow keys and Tab reach the description, and Escape closes it without saving.
Whats-New-De: Schnell hinzufügen: Pfeiltasten und Tab erreichen die Beschreibung, und Escape schließt es, ohne zu speichern.
Whats-New: Sub-projects take their parent's colour unless they have their own.
Whats-New-De: Unterprojekte übernehmen die Farbe ihres übergeordneten Projekts, wenn sie keine eigene haben.
Whats-New: A right click on a task opens its menu, with Move to and more; Delete completed tasks clears a list, with Undo.
Whats-New-De: Ein Rechtsklick auf eine Aufgabe öffnet ihr Menü, mit Verschieben nach und mehr; Erledigte Aufgaben löschen räumt eine Liste auf, mit Rückgängig.
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_de.arb

@@ -132,6 +132,7 @@
   "projectDelete": "Projekt löschen",
   "projectDeleteTitle": "Projekt löschen?",
   "projectDeleteMessage": "„{name}“ wird mit seinen Abschnitten und Aufgaben auf all deinen Geräten gelöscht.",
+  "projectInheritColor": "Gleiche Farbe wie das übergeordnete Projekt",
   "projectParent": "Übergeordnetes Projekt",
   "projectNoParent": "Kein übergeordnetes Projekt",
   "projectFavorite": "Favorit",
@@ -231,7 +232,6 @@
   "taskDuplicated": "Aufgabe dupliziert",
   "subTasksHideDone": "Erledigte Unteraufgaben ausblenden",
   "subTasksShowDone": "Erledigte Unteraufgaben zeigen",
-  "taskClose": "Schließen",
   "taskPath": "Wo die Aufgabe liegt",
   "weekToday": "Zurück zu heute",
   "monthPrevious": "Voriger Monat",
@@ -402,5 +402,7 @@
   "locationOffTitle": "Standort ist für Erinnerungen aus",
   "locationOffHint": "Erinnerungen an einem Ort brauchen „Immer zulassen“.",
   "locationArrived": "Du bist bei {name}",
-  "locationLeft": "Du hast {name} verlassen"
+  "locationLeft": "Du hast {name} verlassen",
+  "tasksDeleteCompleted": "Erledigte Aufgaben löschen",
+  "tasksCompletedDeleted": "{count, plural, =1{1 erledigte Aufgabe gelöscht} other{{count} erledigte Aufgaben gelöscht}}"
 }

apps/todo/halkyon_todo_flutter/lib/l10n/app_en.arb

@@ -282,6 +282,10 @@
       }
     }
   },
+  "projectInheritColor": "Same colour as its parent",
+  "@projectInheritColor": {
+    "description": "In a sub-project's editor: whether it shows in its parent's colour rather than one of its own (the developer's review, 9 Nov 2026)."
+  },
   "projectParent": "Parent project",
   "@projectParent": {
     "description": "A project's editor (ADR 0033, D28), as Todoist's Add project."
@@ -598,7 +602,6 @@
   "taskDuplicated": "Task duplicated",
   "subTasksHideDone": "Hide done sub-tasks",
   "subTasksShowDone": "Show done sub-tasks",
-  "taskClose": "Close",
   "taskPath": "Where the task is",
   "weekToday": "Back to today",
   "monthPrevious": "Previous month",
@@ -1246,5 +1249,18 @@
         "type": "String"
       }
     }
+  },
+  "tasksDeleteCompleted": "Delete completed tasks",
+  "@tasksDeleteCompleted": {
+    "description": "A list's menu: deletes its done tasks, with an Undo (the developer's review, 9 Nov 2026)."
+  },
+  "tasksCompletedDeleted": "{count, plural, =1{1 completed task deleted} other{{count} completed tasks deleted}}",
+  "@tasksCompletedDeleted": {
+    "description": "The snack bar after Delete completed tasks, with its Undo.",
+    "placeholders": {
+      "count": {
+        "type": "int"
+      }
+    }
   }
 }

apps/todo/halkyon_todo_flutter/lib/l10n/app_en_US.arb

@@ -1,5 +1,6 @@
 {
   "@@locale": "en_US",
   "projectFavorite": "Favorite",
-  "favoritesTitle": "Favorites"
+  "favoritesTitle": "Favorites",
+  "projectInheritColor": "Same color as its parent"
 }

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

@@ -892,6 +892,12 @@ abstract class AppLocalizations {
   /// **'\"{name}\" is deleted with its sections and tasks, on all your devices.'**
   String projectDeleteMessage(String name);
 
+  /// In a sub-project's editor: whether it shows in its parent's colour rather than one of its own (the developer's review, 9 Nov 2026).
+  ///
+  /// In en, this message translates to:
+  /// **'Same colour as its parent'**
+  String get projectInheritColor;
+
   /// A project's editor (ADR 0033, D28), as Todoist's Add project.
   ///
   /// In en, this message translates to:
@@ -1486,12 +1492,6 @@ abstract class AppLocalizations {
   /// **'Show done sub-tasks'**
   String get subTasksShowDone;
 
-  /// No description provided for @taskClose.
-  ///
-  /// In en, this message translates to:
-  /// **'Close'**
-  String get taskClose;
-
   /// No description provided for @taskPath.
   ///
   /// In en, this message translates to:
@@ -2517,6 +2517,18 @@ abstract class AppLocalizations {
   /// In en, this message translates to:
   /// **'You\'ve left {name}'**
   String locationLeft(String name);
+
+  /// A list's menu: deletes its done tasks, with an Undo (the developer's review, 9 Nov 2026).
+  ///
+  /// In en, this message translates to:
+  /// **'Delete completed tasks'**
+  String get tasksDeleteCompleted;
+
+  /// The snack bar after Delete completed tasks, with its Undo.
+  ///
+  /// In en, this message translates to:
+  /// **'{count, plural, =1{1 completed task deleted} other{{count} completed tasks deleted}}'**
+  String tasksCompletedDeleted(int count);
 }
 
 class _AppLocalizationsDelegate

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

@@ -487,6 +487,10 @@ class AppLocalizationsDe extends AppLocalizations {
     return '„$name“ wird mit seinen Abschnitten und Aufgaben auf all deinen Geräten gelöscht.';
   }
 
+  @override
+  String get projectInheritColor =>
+      'Gleiche Farbe wie das übergeordnete Projekt';
+
   @override
   String get projectParent => 'Übergeordnetes Projekt';
 
@@ -921,9 +925,6 @@ class AppLocalizationsDe extends AppLocalizations {
   @override
   String get subTasksShowDone => 'Erledigte Unteraufgaben zeigen';
 
-  @override
-  String get taskClose => 'Schließen';
-
   @override
   String get taskPath => 'Wo die Aufgabe liegt';
 
@@ -1574,4 +1575,18 @@ class AppLocalizationsDe extends AppLocalizations {
   String locationLeft(String name) {
     return 'Du hast $name verlassen';
   }
+
+  @override
+  String get tasksDeleteCompleted => 'Erledigte Aufgaben löschen';
+
+  @override
+  String tasksCompletedDeleted(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count erledigte Aufgaben gelöscht',
+      one: '1 erledigte Aufgabe gelöscht',
+    );
+    return '$_temp0';
+  }
 }

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

@@ -487,6 +487,9 @@ class AppLocalizationsEn extends AppLocalizations {
     return '\"$name\" is deleted with its sections and tasks, on all your devices.';
   }
 
+  @override
+  String get projectInheritColor => 'Same colour as its parent';
+
   @override
   String get projectParent => 'Parent project';
 
@@ -921,9 +924,6 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get subTasksShowDone => 'Show done sub-tasks';
 
-  @override
-  String get taskClose => 'Close';
-
   @override
   String get taskPath => 'Where the task is';
 
@@ -1572,6 +1572,20 @@ class AppLocalizationsEn extends AppLocalizations {
   String locationLeft(String name) {
     return 'You\'ve left $name';
   }
+
+  @override
+  String get tasksDeleteCompleted => 'Delete completed tasks';
+
+  @override
+  String tasksCompletedDeleted(int count) {
+    String _temp0 = intl.Intl.pluralLogic(
+      count,
+      locale: localeName,
+      other: '$count completed tasks deleted',
+      one: '1 completed task deleted',
+    );
+    return '$_temp0';
+  }
 }
 
 /// The translations for English, as used in the United Kingdom (`en_GB`).
@@ -1583,6 +1597,9 @@ class AppLocalizationsEnGb extends AppLocalizationsEn {
 class AppLocalizationsEnUs extends AppLocalizationsEn {
   AppLocalizationsEnUs() : super('en_US');
 
+  @override
+  String get projectInheritColor => 'Same color as its parent';
+
   @override
   String get projectFavorite => 'Favorite';