feat(train): Record has a card for each activity, its Start opening the sheet for it (ADR 0030, D60)

The Record tab shows a card per activity it records, the interval plans
below. A card's Start opens the Record sheet for that activity, which
keeps every other choice; the sheet no longer chooses the activity, and
so offers the plans and routes for it or for any. While a recording is
under way or waits to be saved, the cards wait, the bar leading back.

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/train/halkyon_train_flutter/lib/l10n/app_localizations.dart

@@ -166,12 +166,6 @@ abstract class AppLocalizations {
   /// **'Back to the recording'**
   String get recordBack;
 
-  /// No description provided for @recordSheetTitle.
-  ///
-  /// In en, this message translates to:
-  /// **'Record a workout'**
-  String get recordSheetTitle;
-
   /// No description provided for @activityRunning.
   ///
   /// In en, this message translates to:
@@ -3465,6 +3459,12 @@ abstract class AppLocalizations {
   /// In en, this message translates to:
   /// **'{hours, plural, =0{{minutes} min} other{{hours} h {minutes} min}}'**
   String homeWeekDuration(int hours, int minutes);
+
+  /// No description provided for @recordPlansHeading.
+  ///
+  /// In en, this message translates to:
+  /// **'Interval plans'**
+  String get recordPlansHeading;
 }
 
 class _AppLocalizationsDelegate