fix: uni-wizard v2 harness import collision (#716)

Resolves #716. 'from harness import' in v2 modules resolved to
uni-wizard/harness.py instead of uni-wizard/v2/harness.py.

Fix: use importlib.util.spec_from_file_location to explicitly
load from the v2 directory, bypassing sys.path ambiguity.

Fixed files:
- uni-wizard/v2/task_router_daemon.py
- uni-wizard/v2/router.py

Before: 4 integration tests failed (ImportError)
After:  24 passed, 0 failed

uni-wizard/v2/router.py

@@ -18,7 +18,15 @@ from pathlib import Path
 from dataclasses import dataclass
 from enum import Enum
 
-from harness import UniWizardHarness, House, ExecutionResult
+# Import from v2 harness to avoid collision with uni-wizard/harness.py
+import importlib.util as _iutil
+_v2_dir = Path(__file__).parent
+_spec = _iutil.spec_from_file_location("harness", _v2_dir / "harness.py")
+_mod = _iutil.module_from_spec(_spec)
+_spec.loader.exec_module(_mod)
+UniWizardHarness = _mod.UniWizardHarness
+House = _mod.House
+ExecutionResult = _mod.ExecutionResult
 
 
 class TaskType(Enum):

uni-wizard/v2/task_router_daemon.py

@@ -12,11 +12,28 @@ from pathlib import Path
 from datetime import datetime
 from typing import Dict, List, Optional
 
-sys.path.insert(0, str(Path(__file__).parent))
+# Explicit imports from v2 directory to avoid namespace collision
+# with uni-wizard/harness.py at the repo root level
+import importlib.util as _iutil
+_v2_dir = Path(__file__).parent
 
-from harness import UniWizardHarness, House, ExecutionResult
-from router import HouseRouter, TaskType
-from author_whitelist import AuthorWhitelist
+def _load_mod(name):
+    spec = _iutil.spec_from_file_location(name, _v2_dir / f"{name}.py")
+    mod = _iutil.module_from_spec(spec)
+    spec.loader.exec_module(mod)
+    return mod
+
+_harness = _load_mod("harness")
+UniWizardHarness = _harness.UniWizardHarness
+House = _harness.House
+ExecutionResult = _harness.ExecutionResult
+
+_router = _load_mod("router")
+HouseRouter = _router.HouseRouter
+TaskType = _router.TaskType
+
+_whitelist = _load_mod("author_whitelist")
+AuthorWhitelist = _whitelist.AuthorWhitelist
 
 
 class ThreeHouseTaskRouter: