feat(server): add GET /attachment/status with derived boxed qty

Co-Authored-By: Claude <noreply@anthropic.com>

tests/test_attachment_api.py

@@ -28,3 +28,59 @@ def test_categories_lists_active_only(client: TestClient, db: Session):
     assert "TEST_OFF" not in names
     # sorted by sort_order then name
     assert names.index("TEST_CERT") < names.index("TEST_EXTRA")
+
+
+def test_status_unknown_zongpai_is_undetermined(client: TestClient):
+    resp = client.get(
+        "/CargoTrace/attachment/status", params={"zongpai_no": "26BW0011"}
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["zongpai_no"] == "26BW0011"
+    assert data["determination"] == "undetermined"
+    assert data["items"] == []
+    assert data["all_complete"] is False
+
+
+def test_status_invalid_zongpai(client: TestClient):
+    resp = client.get(
+        "/CargoTrace/attachment/status", params={"zongpai_no": "BAD"}
+    )
+    assert resp.status_code == 400
+    assert resp.json()["error_code"] == "INVALID_ZONGPAI"
+
+
+def test_status_reflects_config_and_boxed(client: TestClient, db: Session):
+    cat_ids = _seed_categories(db)
+    cert_id = cat_ids[0]
+    # Plan: 检验证书 expected=80
+    client.put(
+        "/CargoTrace/attachment/config",
+        json={
+            "zongpai_no": "26BW0011",
+            "determination": "has",
+            "items": [{"category_id": cert_id, "expected_qty": 80}],
+        },
+    )
+    # Box 30 of them
+    client.post(
+        "/CargoTrace/attachment/box",
+        json={
+            "zongpai_no": "26BW0011",
+            "category_id": cert_id,
+            "box_no": 921,
+            "quantity": 30,
+        },
+    )
+    resp = client.get(
+        "/CargoTrace/attachment/status", params={"zongpai_no": "26BW0011"}
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["determination"] == "has"
+    assert data["all_complete"] is False
+    item = data["items"][0]
+    assert item["category_id"] == cert_id
+    assert item["expected_qty"] == 80
+    assert item["boxed_qty"] == 30
+    assert item["complete"] is False