feat(app): offer to review first when reviews are due beyond the tags chosen

With tags narrowing a session, new cards of theirs to learn, and cards
of other tags due for review, the session asks first ("You have reviews
due"): Review first studies the reviews due across every tag, round
after round, the tags not applying until none is left (the session
settings say so meanwhile); Learn anyway learns the tags' new cards;
Cancel leaves. A new session asks again.

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

halkyon_learn_flutter/lib/l10n/app_localizations_en.dart

@@ -1659,6 +1659,40 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get studyClose => 'Close session';
 
+  @override
+  String get studyReviewsDueTitle => 'You have reviews due';
+
+  @override
+  String studyReviewsDueBody(int reviews, int news) {
+    String _temp0 = intl.Intl.pluralLogic(
+      reviews,
+      locale: localeName,
+      other: '$reviews cards are',
+      one: '1 card is',
+    );
+    String _temp1 = intl.Intl.pluralLogic(
+      news,
+      locale: localeName,
+      other: '$news new cards',
+      one: '1 new card',
+    );
+    return '$_temp0 due for review. Learning $_temp1 now will add to your review load.';
+  }
+
+  @override
+  String get studyReviewsDueAllTagsNote =>
+      '“Review first” studies the whole backlog across every tag — your tag filter doesn\'t apply until it\'s clear.';
+
+  @override
+  String get studyReviewFirst => 'Review first';
+
+  @override
+  String get studyLearnAnyway => 'Learn anyway';
+
+  @override
+  String get studySettingsTagFilterPausedForBacklog =>
+      'This session is clearing your review backlog across every tag, so these tags aren\'t narrowing it. They apply again to your next session.';
+
   @override
   String get studyBuryCard => 'Bury until tomorrow';