feat: delete habits from detail sheet

tests/test_mvp_backend.py

@@ -272,6 +272,22 @@ def test_habits_numeric_accumulation_pause_archive_grid_and_stats(client):
     assert client.get(f"/api/v1/habits/{habit_id}/stats").json()["total"] == 8
 
 
+def test_habit_permanent_delete_removes_habit_and_history(client):
+    boot(client)
+    created = client.post(
+        "/api/v1/habits",
+        json={"name": "待删除习惯", "kind": "numeric", "target": 3, "schedule_type": "daily"},
+    )
+    habit_id = created.json()["id"]
+    today = datetime.now(UTC).date().isoformat()
+    assert client.put(f"/api/v1/habits/{habit_id}/logs/{today}", json={"value": 2}).status_code == 200
+
+    assert client.delete(f"/api/v1/habits/{habit_id}/permanent").status_code == 204
+    assert all(row["id"] != habit_id for row in client.get("/api/v1/habits").json())
+    assert all(row["id"] != habit_id for row in client.get("/api/v1/habits", params={"archived": True}).json())
+    assert client.get(f"/api/v1/habits/{habit_id}/stats").status_code == 404
+
+
 def test_boolean_interval_habit_schedule(client):
     boot(client)
     habit = client.post(