feat(assistant): ask Claude from Home, the Library, a studyset and a session

A device setting, off unless the person turns it on (Settings ›
Assistant), shows a field at the foot of Home and a button that unfolds
into one: above Create studyset in the Library (smaller), in the free lane
on the right of a studyset's bottom bar (floating alone from expanded
windows on), and in the card's lower right corner while studying.

A question is handed to Claude, not answered here: the app opens
claude.ai/new with the question written in, followed by what it is about
(the person's learning on the instance, a studyset by name, or the studied
card's front and back as text), cut at 12,000 characters, for the person
to read and send in Claude. A Claude plan can't drive a chat inside
another app, as Anthropic allows no third party to offer sign-in with it;
Claude is to read the studysets through a connector on the instance
instead (next). Nothing leaves the app until the person sends it there.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MMm7usAo6q9ZZRoPkWjoxi
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/lib/l10n/app_localizations.dart

@@ -9074,6 +9074,94 @@ abstract class AppLocalizations {
   /// In en, this message translates to:
   /// **'Words with it'**
   String get kanjiExampleWords;
+
+  /// No description provided for @settingsAssistant.
+  ///
+  /// In en, this message translates to:
+  /// **'Assistant'**
+  String get settingsAssistant;
+
+  /// No description provided for @settingsAskClaude.
+  ///
+  /// In en, this message translates to:
+  /// **'Ask Claude'**
+  String get settingsAskClaude;
+
+  /// No description provided for @settingsAskClaudeSubtitle.
+  ///
+  /// In en, this message translates to:
+  /// **'Off unless you turn it on. Adds a field on Home and a button in the Library, on a studyset and while studying. A question opens in Claude with what it is about, and you send it there; nothing is sent from here.'**
+  String get settingsAskClaudeSubtitle;
+
+  /// No description provided for @assistantHint.
+  ///
+  /// In en, this message translates to:
+  /// **'Ask Claude…'**
+  String get assistantHint;
+
+  /// No description provided for @assistantHintStudyset.
+  ///
+  /// In en, this message translates to:
+  /// **'Ask Claude about {title}…'**
+  String assistantHintStudyset(String title);
+
+  /// No description provided for @assistantHintCard.
+  ///
+  /// In en, this message translates to:
+  /// **'Ask Claude about this card…'**
+  String get assistantHintCard;
+
+  /// No description provided for @assistantSend.
+  ///
+  /// In en, this message translates to:
+  /// **'Ask in Claude'**
+  String get assistantSend;
+
+  /// No description provided for @assistantOpen.
+  ///
+  /// In en, this message translates to:
+  /// **'Ask Claude'**
+  String get assistantOpen;
+
+  /// No description provided for @assistantClose.
+  ///
+  /// In en, this message translates to:
+  /// **'Close'**
+  String get assistantClose;
+
+  /// No description provided for @assistantOpenFailed.
+  ///
+  /// In en, this message translates to:
+  /// **'Claude couldn\'t be opened.'**
+  String get assistantOpenFailed;
+
+  /// What the app hands to Claude: the person's question, then where it was asked. Written as the person, to Claude.
+  ///
+  /// In en, this message translates to:
+  /// **'{question}\n\n(Asked from Halkyon Learn, where I learn with studysets on {instance}. If you have the Halkyon Learn connector, you can read them there.)'**
+  String assistantPromptLearning(String question, String instance);
+
+  /// No description provided for @assistantPromptStudyset.
+  ///
+  /// In en, this message translates to:
+  /// **'{question}\n\n(About my studyset “{title}” in Halkyon Learn on {instance}. If you have the Halkyon Learn connector, you can read it there.)'**
+  String assistantPromptStudyset(
+    String question,
+    String title,
+    String instance,
+  );
+
+  /// No description provided for @assistantPromptCard.
+  ///
+  /// In en, this message translates to:
+  /// **'{question}\n\n(About a flashcard I am studying, in my studyset “{title}” in Halkyon Learn on {instance}.\nFront: {front}\nBack: {back})'**
+  String assistantPromptCard(
+    String question,
+    String title,
+    String front,
+    String back,
+    String instance,
+  );
 }
 
 class _AppLocalizationsDelegate