feat(selection): show stock industry and concept boards in detail panel

Add point-in-time stock membership lookup to the sector radar module
(GET /sector-radar/stocks/{ts_code}/membership) reading the existing
dc_index/dc_member snapshots, and surface industries plus concept chips
in the selection signal detail panel with graceful no-data hiding.

zhixing-server/tests/test_sector_radar_http.py

@@ -13,6 +13,9 @@ from zhixing_server.modules.sector_radar.application.read import (
     RadarQuery,
     RadarView,
     RankingPage,
+    SectorRef,
+    StockSectorMembership,
+    StockSectorQuery,
 )
 from zhixing_server.modules.sector_radar.domain.metrics import AmountNetStrategy
 from zhixing_server.modules.sector_radar.domain.models import (
@@ -87,7 +90,9 @@ def _ranking() -> RankedMetric:
 class FakeReader:
     def __init__(self, *, no_data: bool = False, fail: bool = False) -> None:
         self.fail = fail
+        self.no_data = no_data
         self.last_query: RadarQuery | None = None
+        self.last_membership_query: StockSectorQuery | None = None
         success = _publication("publication-success", PublicationStatus.SUCCESS)
         current = _publication(
             "publication-partial",
@@ -125,6 +130,32 @@ class FakeReader:
         self.last_query = query
         return replace(self.page, query=query)
 
+    def stock_membership(self, query: StockSectorQuery) -> StockSectorMembership:
+        if self.fail:
+            raise SectorRadarRepositoryError("private database detail")
+        self.last_membership_query = query
+        if self.no_data:
+            return StockSectorMembership(
+                status="no_data",
+                query=query,
+                trade_date=None,
+                industries=(),
+                concepts=(),
+                concept_total=0,
+            )
+        return StockSectorMembership(
+            status="success",
+            query=query,
+            trade_date=TARGET_DATE,
+            industries=(SectorRef(code="BK0901.DC", name="银行"),),
+            concepts=(
+                SectorRef(code="BK0001.DC", name="机器人"),
+                SectorRef(code="BK0002.DC", name="人工智能"),
+                SectorRef(code="BK0003.DC", name="数字经济"),
+            ),
+            concept_total=3,
+        )
+
 
 def _client(reader: FakeReader) -> TestClient:
     application = create_app()
@@ -228,3 +259,78 @@ def test_repository_error_maps_to_redacted_503() -> None:
         }
     }
     assert "private database detail" not in response.text
+
+
+def test_stock_membership_maps_industries_and_concepts() -> None:
+    reader = FakeReader()
+    response = _client(reader).get(
+        "/api/v1/sector-radar/stocks/000001.SZ/membership",
+        params={"trade_date": "2026-08-28"},
+    )
+
+    assert response.status_code == 200
+    assert reader.last_membership_query == StockSectorQuery(
+        trade_date=TARGET_DATE,
+        ts_code="000001.SZ",
+    )
+    payload = response.json()
+    assert payload["status"] == "success"
+    assert payload["ts_code"] == "000001.SZ"
+    assert payload["requested_trade_date"] == "2026-08-28"
+    assert payload["trade_date"] == "2026-08-28"
+    assert payload["industries"] == [{"code": "BK0901.DC", "name": "银行"}]
+    assert payload["concept_total"] == 3
+    assert payload["concept_limit"] == 20
+    assert [concept["code"] for concept in payload["concepts"]] == [
+        "BK0001.DC",
+        "BK0002.DC",
+        "BK0003.DC",
+    ]
+
+
+def test_stock_membership_no_data_is_a_stable_200_response() -> None:
+    response = _client(FakeReader(no_data=True)).get(
+        "/api/v1/sector-radar/stocks/000001.SZ/membership",
+        params={"trade_date": "2026-08-28"},
+    )
+
+    assert response.status_code == 200
+    payload = response.json()
+    assert payload["status"] == "no_data"
+    assert payload["trade_date"] is None
+    assert payload["industries"] == []
+    assert payload["concepts"] == []
+    assert payload["concept_total"] == 0
+
+
+def test_stock_membership_rejects_invalid_query_values() -> None:
+    client = _client(FakeReader())
+
+    missing_date = client.get("/api/v1/sector-radar/stocks/000001.SZ/membership")
+    bad_limit = client.get(
+        "/api/v1/sector-radar/stocks/000001.SZ/membership",
+        params={"trade_date": "2026-08-28", "concept_limit": 0},
+    )
+    over_limit = client.get(
+        "/api/v1/sector-radar/stocks/000001.SZ/membership",
+        params={"trade_date": "2026-08-28", "concept_limit": 101},
+    )
+    empty_code = client.get(
+        "/api/v1/sector-radar/stocks//membership", params={"trade_date": "2026-08-28"}
+    )
+
+    assert missing_date.status_code == 422
+    assert bad_limit.status_code == 422
+    assert over_limit.status_code == 422
+    assert empty_code.status_code in (404, 422)
+
+
+def test_stock_membership_repository_error_maps_to_redacted_503() -> None:
+    response = _client(FakeReader(fail=True)).get(
+        "/api/v1/sector-radar/stocks/000001.SZ/membership",
+        params={"trade_date": "2026-08-28"},
+    )
+
+    assert response.status_code == 503
+    assert response.json()["detail"]["code"] == "sector_radar_storage_unavailable"
+    assert "private database detail" not in response.text