fix(charts): simplify time labels in investigation views

src/features/agent/answer-ui/answer-display-time.test.ts

@@ -17,7 +17,7 @@ describe("answer presentation time zone", () => {
     expect(result.elements.table.props.rows).toEqual([["2026/7/16 08:00:00（UTC+8）"]]);
     expect(result.elements.evidence.props.observed_at).toBe("2026/7/16 08:00:00（UTC+8）");
     expect(result.elements.evidence.props.evidence_id).toBe("2026-07-16T00:00:00Z");
-    expect(result.elements.chart.props.x_axis_name).toBe("时间（UTC+8）");
+    expect(result.elements.chart.props.x_axis_name).toBe("时间");
     expect(result.elements.chart.props.x_data).toEqual(["08:00"]);
     expect(JSON.stringify(spec)).toBe(original);
     expect(withAnswerDisplayTimes(result)).toEqual(result);
@@ -36,4 +36,23 @@ describe("answer presentation time zone", () => {
     expect(result.elements.table.props.rows).toEqual([["2027/1/1 01:00:00（UTC+8）", "00:00"]]);
     expect(withAnswerDisplayTimes(result)).toEqual(result);
   });
+  it("removes chart timezone wording while preserving the window, data and sample instants", () => {
+    const samples = ["2026-07-15T23:30:00Z", "2026-07-15T23:45:00Z"];
+    const spec: Spec = { root: "chart", elements: {
+      chart: { type: "Chart", props: {
+        title: "回放流量：487434（m³/h，上海时间 07-16 04:45–07:45）",
+        x_axis_name: "上海时间", x_data: ["07:30", "07:45"],
+        series: [{ name: "当前回放（2026-07-16，UTC+8）", data: [420, 380], sample_times: samples }]
+      }, children: [] }
+    } };
+    const result = withAnswerDisplayTimes(spec);
+    expect(result.elements.chart.props.title).toBe("回放流量：487434（m³/h，07-16 04:45–07:45）");
+    expect(result.elements.chart.props.x_axis_name).toBe("时间");
+    expect(result.elements.chart.props.x_data).toEqual(["07:30", "07:45"]);
+    expect(result.elements.chart.props.series).toEqual([
+      { name: "当前回放（2026-07-16）", data: [420, 380], sample_times: samples }
+    ]);
+    expect(withAnswerDisplayTimes(result)).toEqual(result);
+  });
+
 });