[codex] Fix schedule labels and briefing order

[utopiafar]

Summary

• Recompute schedule day headers from day_date at render time so stale Today/Tomorrow labels update across date boundaries.
• Refresh the schedule page relative-date reference when the app resumes or the local day changes.
• Stop auto-pinning the schedule briefing card at the top of the home feed; merge it by timestamp as a normal timeline card.
• Add unit and widget coverage for relative labels, mixed day labels, and briefing-card feed ordering.

Validation

• flutter pub get --offline
• flutter analyze --no-pub lib/ui/schedule/models/schedule_day_label.dart lib/ui/schedule/widgets/schedule_aggregator_screen.dart lib/ui/schedule/widgets/tabs/magazine_narrative_tab.dart test/ui/schedule/models/schedule_day_label_test.dart test/ui/schedule/widgets/schedule_widgets_test.dart
• flutter analyze --no-pub lib/ui/timeline/models/schedule_briefing_merge.dart lib/ui/timeline/view_models/timeline_viewmodel.dart test/ui/timeline/models/schedule_briefing_merge_test.dart
• env -u http_proxy -u https_proxy -u ws_proxy -u wss_proxy NO_PROXY=localhost,127.0.0.1 no_proxy=localhost,127.0.0.1 flutter test --no-pub test/ui/schedule/models/schedule_day_label_test.dart test/ui/schedule/widgets/schedule_widgets_test.dart
• env -u http_proxy -u https_proxy -u ws_proxy -u wss_proxy NO_PROXY=localhost,127.0.0.1 no_proxy=localhost,127.0.0.1 flutter test --no-pub test/ui/schedule test/domain/models/schedule_aggregation_model_test.dart
• env -u http_proxy -u https_proxy -u ws_proxy -u wss_proxy NO_PROXY=localhost,127.0.0.1 no_proxy=localhost,127.0.0.1 flutter test --no-pub test/ui/timeline/models/schedule_briefing_merge_test.dart test/ui/schedule test/domain/models/schedule_aggregation_model_test.dart test/data/repositories/get_schedule_briefing_timeline_card_test.dart

[github-actions]

PR Policy Preflight / PR 规则预检

• Decision / 判定: HIGH RISK / 高风险
• Risk score / 风险分: 10
• Changed files / 变更文件数: 13
• Changed lines / 变更行数: 585
• Diff truncated / Diff 是否截断: false

Findings / 规则命中

• high / 高风险 sensitive-keyword lib/ui/schedule/widgets/tabs/magazine_narrative_tab.dart
  • EN: UserStorage reference changed.
  • 中文: UserStorage 引用发生变化。

Shadow mode: this result is informational and does not block merge.

Shadow mode：当前结果仅供参考，不会阻塞合并。