feat(todo): rows in rounded boxes, Today as Todoist's, lists pulled to sync, a project's own colour

From the developer's review of 3 Nov 2026 (ADR 0033, D19 to D21):
- Today's tab shows today's day in its calendar, Browse the menu's lines,
  Display's button Lucide's square-menu.
- A task's row stands in a rounded box, the rows of a list a group rounded
  at its ends; the box is the row's own surface, so a chosen row's colour no
  longer shows under Upcoming's pinned week strip as the list scrolls. Its
  project and section end the line of its date at the row's right edge.
- Today has at most two groups: what is overdue, folding under its heading,
  and today's, headed "Tuesday, 3 Nov" ("Dienstag, 3. Nov."), without a
  "· Today" after it; Upcoming's days take the same form.
- Upcoming's way back to today shows whenever another day is picked.
- Today, Upcoming, the Inbox and every project pulled down sync now, an
  empty list too, as Learn's.
- A project's screen washes in its own colour, as a studyset's in Learn.
- "Add section" in place of "New section".

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

@@ -60,7 +60,7 @@
   "projectGone": "Dieses Projekt wurde gelöscht.",
   "projectMenu": "Mehr",
   "projectPickTitle": "Projekt",
-  "sectionAdd": "Neuer Abschnitt",
+  "sectionAdd": "Abschnitt hinzufügen",
   "sectionEdit": "Abschnitt umbenennen",
   "sectionDelete": "Abschnitt löschen",
   "sectionDeleteTitle": "Abschnitt löschen?",
@@ -243,5 +243,8 @@
   "snoozeTitle": "Schlummern für",
   "snoozeMinutes": "{count, plural, =1{1 Minute} other{{count} Minuten}}",
   "reminderSnooze": "{count} Min. schlummern",
-  "monthMore": "{count} weitere"
+  "monthMore": "{count} weitere",
+  "dayHeadingPattern": "EEEE, d. MMM",
+  "overdueHide": "Überfälliges ausblenden",
+  "overdueShow": "Überfälliges einblenden"
 }

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

@@ -114,7 +114,7 @@
   "projectGone": "This project was deleted.",
   "projectMenu": "More",
   "projectPickTitle": "Project",
-  "sectionAdd": "New section",
+  "sectionAdd": "Add section",
   "sectionEdit": "Rename section",
   "sectionDelete": "Delete section",
   "sectionDeleteTitle": "Delete the section?",
@@ -778,5 +778,11 @@
         "type": "int"
       }
     }
-  }
+  },
+  "dayHeadingPattern": "EEEE, d MMM",
+  "@dayHeadingPattern": {
+    "description": "intl's DateFormat pattern of a day's heading in Today and Upcoming, as Todoist's (\"Tuesday, 3 Nov\"): EEEE the weekday, d the day, MMM the short month."
+  },
+  "overdueHide": "Hide what is overdue",
+  "overdueShow": "Show what is overdue"
 }

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

@@ -463,7 +463,7 @@ abstract class AppLocalizations {
   /// No description provided for @sectionAdd.
   ///
   /// In en, this message translates to:
-  /// **'New section'**
+  /// **'Add section'**
   String get sectionAdd;
 
   /// No description provided for @sectionEdit.
@@ -1563,6 +1563,24 @@ abstract class AppLocalizations {
   /// In en, this message translates to:
   /// **'{count} more'**
   String monthMore(int count);
+
+  /// intl's DateFormat pattern of a day's heading in Today and Upcoming, as Todoist's ("Tuesday, 3 Nov"): EEEE the weekday, d the day, MMM the short month.
+  ///
+  /// In en, this message translates to:
+  /// **'EEEE, d MMM'**
+  String get dayHeadingPattern;
+
+  /// No description provided for @overdueHide.
+  ///
+  /// In en, this message translates to:
+  /// **'Hide what is overdue'**
+  String get overdueHide;
+
+  /// No description provided for @overdueShow.
+  ///
+  /// In en, this message translates to:
+  /// **'Show what is overdue'**
+  String get overdueShow;
 }
 
 class _AppLocalizationsDelegate

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

@@ -212,7 +212,7 @@ class AppLocalizationsDe extends AppLocalizations {
   String get projectPickTitle => 'Projekt';
 
   @override
-  String get sectionAdd => 'Neuer Abschnitt';
+  String get sectionAdd => 'Abschnitt hinzufügen';
 
   @override
   String get sectionEdit => 'Abschnitt umbenennen';
@@ -966,4 +966,13 @@ class AppLocalizationsDe extends AppLocalizations {
   String monthMore(int count) {
     return '$count weitere';
   }
+
+  @override
+  String get dayHeadingPattern => 'EEEE, d. MMM';
+
+  @override
+  String get overdueHide => 'Überfälliges ausblenden';
+
+  @override
+  String get overdueShow => 'Überfälliges einblenden';
 }

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

@@ -212,7 +212,7 @@ class AppLocalizationsEn extends AppLocalizations {
   String get projectPickTitle => 'Project';
 
   @override
-  String get sectionAdd => 'New section';
+  String get sectionAdd => 'Add section';
 
   @override
   String get sectionEdit => 'Rename section';
@@ -965,6 +965,15 @@ class AppLocalizationsEn extends AppLocalizations {
   String monthMore(int count) {
     return '$count more';
   }
+
+  @override
+  String get dayHeadingPattern => 'EEEE, d MMM';
+
+  @override
+  String get overdueHide => 'Hide what is overdue';
+
+  @override
+  String get overdueShow => 'Show what is overdue';
 }
 
 /// The translations for English, as used in the United Kingdom (`en_GB`).