feat(journal): replace briefing surface with journal; remove news/RSS

The backend retired /api/briefing/* and the RSS feature entirely. This
Flutter change mirrors what landed web-side: rename the briefing surface
to journal, repoint at /api/journal/*, and drop the news/RSS UI since
its endpoints no longer exist.

New (mirrors briefing structure with adapted shapes):
- lib/data/api/journal_api.dart — getToday, getDay, getDays, triggerPrep
- lib/data/models/journal_day.dart — {day_date, conversation, messages}
- lib/providers/journal_provider.dart — async notifier, sendReply, polling,
  silent refresh, regeneratePrep. Mirrors the briefing notifier 1:1
- lib/widgets/journal_prep_card.dart — adapted briefing_digest_card
- lib/screens/journal/journal_screen.dart — adapted briefing_screen,
  weather card preserved (rendered from msg_metadata.sections.weather
  on the daily-prep assistant message). News cards / RSS reactions /
  article-discuss removed
- lib/screens/journal/journal_history_screen.dart — past days picker
  pulls /api/journal/days, drills into /api/journal/day/<iso>

Wiring:
- Routes.briefing → Routes.journal (constants.dart)
- Routes.news removed
- briefingApiProvider → journalApiProvider (api_client_provider.dart)
- newsApiProvider removed
- app.dart: shell tab "Briefing" → "Journal"; News destination removed
  from nav rail, bottom nav, and the More sheet
- splash_screen.dart and login_screen.dart: redirect Routes.journal
  instead of Routes.briefing
- chat_api.dart: drop openArticleInChat (calls deleted /api/chat/from-article)
- settings_provider.dart: drop rssEnabled getter and rssEnabledProvider

Deleted:
- lib/screens/briefing/ (whole directory)
- lib/screens/news/ (whole directory)
- lib/data/api/briefing_api.dart, news_api.dart
- lib/data/models/briefing_conversation.dart, briefing_feed.dart, news_item.dart
- lib/providers/briefing_provider.dart, news_provider.dart
- lib/widgets/briefing_digest_card.dart, news_card.dart
- test cases for NewsItem and BriefingFeed in test/widget_test.dart

flutter analyze: 0 issues.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

lib/data/models/briefing_conversation.dart

@@ -1,35 +0,0 @@
-import 'message.dart';
-
-class BriefingConversation {
-  final int id;
-  final String title;
-  final String? briefingDate; // YYYY-MM-DD or null
-  final List<Message> messages;
-
-  const BriefingConversation({
-    required this.id,
-    required this.title,
-    this.briefingDate,
-    required this.messages,
-  });
-
-  factory BriefingConversation.fromJson(Map<String, dynamic> json) {
-    final rawMessages = json['messages'] as List<dynamic>? ?? [];
-    return BriefingConversation(
-      id: json['id'] as int,
-      title: json['title'] as String? ?? '',
-      briefingDate: json['briefing_date'] as String?,
-      messages: rawMessages
-          .map((e) => Message.fromJson(e as Map<String, dynamic>))
-          .toList(),
-    );
-  }
-
-  BriefingConversation copyWith({List<Message>? messages}) =>
-      BriefingConversation(
-        id: id,
-        title: title,
-        briefingDate: briefingDate,
-        messages: messages ?? this.messages,
-      );
-}

lib/data/models/briefing_feed.dart

@@ -1,20 +0,0 @@
-class BriefingFeed {
-  final int id;
-  final String title;
-  final String url;
-  final String? category;
-
-  const BriefingFeed({
-    required this.id,
-    required this.title,
-    required this.url,
-    this.category,
-  });
-
-  factory BriefingFeed.fromJson(Map<String, dynamic> json) => BriefingFeed(
-        id: json['id'] as int,
-        title: json['title'] as String? ?? '',
-        url: json['url'] as String? ?? '',
-        category: json['category'] as String?,
-      );
-}

lib/data/models/journal_day.dart

@@ -0,0 +1,60 @@
+import 'message.dart';
+
+/// Lightweight conversation header for a journal day — just enough to drive
+/// navigation and labels. The full message list comes alongside in [JournalDay].
+class JournalConversation {
+  final int id;
+  final String title;
+  final String conversationType;
+  final String? dayDate; // YYYY-MM-DD or null
+
+  const JournalConversation({
+    required this.id,
+    required this.title,
+    required this.conversationType,
+    this.dayDate,
+  });
+
+  factory JournalConversation.fromJson(Map<String, dynamic> json) =>
+      JournalConversation(
+        id: json['id'] as int,
+        title: json['title'] as String? ?? '',
+        conversationType:
+            json['conversation_type'] as String? ?? 'journal',
+        dayDate: json['day_date'] as String?,
+      );
+}
+
+/// Payload returned by GET /api/journal/today and /api/journal/day/&lt;iso&gt;.
+/// `conversation` is null on a day with no journal content yet (rare —
+/// the today endpoint creates it on demand).
+class JournalDay {
+  final String dayDate;
+  final JournalConversation? conversation;
+  final List<Message> messages;
+
+  const JournalDay({
+    required this.dayDate,
+    required this.conversation,
+    required this.messages,
+  });
+
+  factory JournalDay.fromJson(Map<String, dynamic> json) {
+    final convRaw = json['conversation'] as Map<String, dynamic>?;
+    final rawMessages = json['messages'] as List<dynamic>? ?? [];
+    return JournalDay(
+      dayDate: json['day_date'] as String,
+      conversation:
+          convRaw == null ? null : JournalConversation.fromJson(convRaw),
+      messages: rawMessages
+          .map((e) => Message.fromJson(e as Map<String, dynamic>))
+          .toList(),
+    );
+  }
+
+  JournalDay copyWith({List<Message>? messages}) => JournalDay(
+        dayDate: dayDate,
+        conversation: conversation,
+        messages: messages ?? this.messages,
+      );
+}

lib/data/models/news_item.dart

@@ -1,37 +0,0 @@
-class NewsItem {
-  final int id;
-  final String title;
-  final String url;
-  final String snippet;
-  final String source;
-  final DateTime? publishedAt;
-  final List<String> topics;
-  final String? reaction;
-
-  const NewsItem({
-    required this.id,
-    required this.title,
-    required this.url,
-    required this.snippet,
-    required this.source,
-    this.publishedAt,
-    required this.topics,
-    this.reaction,
-  });
-
-  factory NewsItem.fromJson(Map<String, dynamic> json) => NewsItem(
-        id: json['id'] as int,
-        title: json['title'] as String? ?? '',
-        url: json['url'] as String? ?? '',
-        snippet: json['snippet'] as String? ?? '',
-        source: json['source'] as String? ?? '',
-        publishedAt: json['published_at'] != null
-            ? DateTime.tryParse(json['published_at'] as String)
-            : null,
-        topics: (json['topics'] as List<dynamic>?)
-                ?.cast<String>()
-                .toList() ??
-            [],
-        reaction: json['reaction'] as String?,
-      );
-}