Merge remote main with teacher streaming and composer updates

.project-docs/10-decisions/decision-index.md

@@ -52,3 +52,5 @@ Create or update an ADR when a choice affects:
 - data model
 - long-term maintenance
 - user-facing workflow
+
+- 2026-09-29 远程输入区与本地流式输出合并：[老师模型与语音、时间戳及独立介绍](ADR-2026-09-22-coding-teacher.md)保留项目聊天和云端人设；[桌面窗口／空作品预览边界](../20-architecture/system-overview.md#integrated-desktop-and-consultation-boundaries-2026-09-29)由 Main 持有。模型选择配套服务仍需单独上线。