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>

tests/fakes/__init__.py

@@ -0,0 +1,29 @@
+"""Test double dùng chung cho cả 3 team — không phụ thuộc Qt.
+
+Gói này cố ý không import sẵn fake nào để tránh kéo theo phụ thuộc khi chạy cô lập.
+Hỗ trợ import trực tiếp từ module con hoặc import lười từ package.
+"""
+from typing import Any
+
+
+def __getattr__(name: str) -> Any:
+    if name in ("FakeProvider", "RecordedCall", "ScriptedTurn"):
+        from .fake_provider import FakeProvider, RecordedCall, ScriptedTurn
+        return locals()[name]
+    if name in ("FakeToolExecutor", "ToolInvocation"):
+        from .fake_tool_executor import FakeToolExecutor, ToolInvocation
+        return locals()[name]
+    if name == "FakeClock":
+        from .fake_clock import FakeClock
+        return FakeClock
+    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")
+
+
+__all__ = [
+    "FakeClock",
+    "FakeProvider",
+    "FakeToolExecutor",
+    "RecordedCall",
+    "ScriptedTurn",
+    "ToolInvocation",
+]