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/shell/branding.py

@@ -0,0 +1,26 @@
+"""Tên gọi và biểu tượng của ứng dụng — R08-T10.
+
+Tách riêng vì cả cửa sổ chính lẫn thanh trên cùng đều cần, mà để ở một trong
+hai thì file kia phải import ngược lại — vòng import.
+"""
+from __future__ import annotations
+
+from pathlib import Path
+
+from PySide6.QtGui import QIcon
+
+#: branding.py nằm sâu 2 cấp nên phải trỏ ngược lên gốc gói.
+ASSETS = Path(__file__).resolve().parents[2] / "assets"
+
+
+def app_icon() -> QIcon:
+    """The buffalo app icon, used everywhere (window title bar, Windows taskbar and
+    the tray). The multi-size ``.ico`` is loaded FIRST so Windows has the right
+    pixmap for the taskbar; the high-res ``.png`` is added so the icon stays crisp
+    at large sizes. This keeps the taskbar icon identical to the app's icon."""
+    icon = QIcon()
+    for name in ("icon.ico", "icon.png"):
+        path = ASSETS / name
+        if path.exists():
+            icon.addFile(str(path))
+    return icon