Feature/delta team/epic r04 (#7)

## Summary

epic r04 - begin refactor

## Change Type

- [x] Cowork feature
- [ ] Bug fix
- [ ] Core AI contribution
- [ ] Test / hardening
- [ ] Performance
- [ ] Documentation

## Related Work

Cowork Task:

Core Repo: http://34.143.229.138/gitea-admin/fsg-ai-core-assets

Core AI Issue:

Core Task:

Related PR:

## Scope

What is intentionally included?

What is intentionally NOT included?

## Validation

- [ ] Unit tests
- [ ] Integration tests
- [ ] Manual verification
- [ ] Regression check

Commands / evidence:

## Security Impact

Permission / credential / network / customer data impact:

## Compatibility

- [ ] No breaking change
- [ ] Breaking change documented

## Reviewer Notes

Anything Cowork reviewers should pay attention to.

---------

Co-authored-by: Anh Tran Nguyen Minh <anhtnm1@fpt.com>
Co-authored-by: Huong Le Thi Thien <huongltt35@fpt.com>
Co-authored-by: Nam Pham Dinh Thanh <nampdt@fpt.com>
Co-authored-by: Vu Dam Tuan <vudt15@fpt.com>
Co-authored-by: Hiep Ha Van <hiephv3@fpt.com>
Co-authored-by: Lam Hoang Van <lamhv7@fpt.com>
Reviewed-on: #7
Co-authored-by: Duy Le Huu <duylh19@fpt.com>

presentation/chat/__init__.py

@@ -0,0 +1,34 @@
+"""Presentation chat package (EPIC R08 - Chat UI Hub).
+
+Contains single-responsibility components and mixins for the unified chat interface:
+- ChatPanel: container shell for streaming chat turns, worker thread management, and history.
+- ChatHistoryWidget / ChatView / MessageBubble: scrollable message timeline and markdown renderers.
+- Composer / ComposerWidget: input box, command dispatch, attachments list, and message queue.
+- AttachmentMixin: attachment security check, character limit, and prompt augmentation.
+- AudioRecorderWidget: audio/voice recording button and timer status.
+- OutputPanelMixin: output files manager and directory watcher.
+"""
+from __future__ import annotations
+
+from .attachment_picker import AttachmentMixin
+from .audio_recorder_widget import AudioRecorderWidget
+from .chat_history_widget import ChatHistoryWidget, ChatView, MessageBubble
+from .chat_output_panel import OutputPanelMixin
+from .chat_panel import ChatPanel
+from .composer_widget import Composer, ComposerWidget
+
+# ``ChatOutputPanelMixin`` từng nằm trong danh sách này nhưng module không hề
+# export cái tên đó — tên thật là ``OutputPanelMixin`` (đã có ở dưới). Khai một
+# tên không tồn tại làm ``from ... import *`` ném AttributeError, và ``__all__``
+# thì không có bước kiểm nào bắt được. Đã gỡ.
+__all__ = [
+    "AttachmentMixin",
+    "AudioRecorderWidget",
+    "ChatHistoryWidget",
+    "ChatPanel",
+    "ChatView",
+    "Composer",
+    "ComposerWidget",
+    "MessageBubble",
+    "OutputPanelMixin",
+]