test: remediate and stabilize auxiliary backend and frontend tests

- Standardized task log, LLM provider, and report profile tests.
- Relocated auxiliary tests into __tests__ directories for consistency.
- Updated git_service and defensive guards with minor stability fixes discovered during testing.
- Added UX integration tests for the reports list component.

backend/src/api/routes/__tests__/test_tasks_logs.py

@@ -0,0 +1,73 @@
+# [DEF:__tests__/test_tasks_logs:Module]
+# @RELATION: VERIFIES -> ../tasks.py
+# @PURPOSE: Contract testing for task logs API endpoints.
+# [/DEF:__tests__/test_tasks_logs:Module]
+
+import pytest
+from fastapi import FastAPI
+from fastapi.testclient import TestClient
+from unittest.mock import MagicMock
+from src.dependencies import get_task_manager, has_permission
+from src.api.routes.tasks import router
+
+# @TEST_FIXTURE: mock_app
+@pytest.fixture
+def client():
+    app = FastAPI()
+    app.include_router(router, prefix="/tasks")
+    
+    # Mock TaskManager
+    mock_tm = MagicMock()
+    app.dependency_overrides[get_task_manager] = lambda: mock_tm
+    
+    # Mock permissions (bypass for unit test)
+    app.dependency_overrides[has_permission("tasks", "READ")] = lambda: True
+    
+    return TestClient(app), mock_tm
+
+# @TEST_CONTRACT: get_task_logs_api -> Invariants
+# @TEST_FIXTURE: valid_task_logs_request
+def test_get_task_logs_success(client):
+    tc, tm = client
+    
+    # Setup mock task
+    mock_task = MagicMock()
+    tm.get_task.return_value = mock_task
+    tm.get_task_logs.return_value = [{"level": "INFO", "message": "msg1"}]
+    
+    response = tc.get("/tasks/task-1/logs?level=INFO")
+    
+    assert response.status_code == 200
+    assert response.json() == [{"level": "INFO", "message": "msg1"}]
+    tm.get_task.assert_called_with("task-1")
+    # Verify filter construction inside route
+    args = tm.get_task_logs.call_args
+    assert args[0][0] == "task-1"
+    assert args[0][1].level == "INFO"
+
+# @TEST_EDGE: task_not_found
+def test_get_task_logs_not_found(client):
+    tc, tm = client
+    tm.get_task.return_value = None
+    
+    response = tc.get("/tasks/missing/logs")
+    assert response.status_code == 404
+    assert response.json()["detail"] == "Task not found"
+
+# @TEST_EDGE: invalid_limit
+def test_get_task_logs_invalid_limit(client):
+    tc, tm = client
+    # limit=0 is ge=1 in Query
+    response = tc.get("/tasks/task-1/logs?limit=0")
+    assert response.status_code == 422
+
+# @TEST_INVARIANT: response_purity
+def test_get_task_log_stats_success(client):
+    tc, tm = client
+    tm.get_task.return_value = MagicMock()
+    tm.get_task_log_stats.return_value = {"INFO": 5, "ERROR": 1}
+    
+    response = tc.get("/tasks/task-1/logs/stats")
+    assert response.status_code == 200
+    # response_model=LogStats might wrap this, but let's check basic structure
+    # assuming tm.get_task_log_stats returns something compatible with LogStats