test: 重构测试体系 — 建立组件测试层、补充后端测试、清理低质量测试

- 新增 jsdom + @testing-library/react 组件测试环境
- 新增 12 个组件测试，覆盖所有前端组件
- 补充后端 middleware 和 helpers 单元测试
- 删除伪测试 use-target-detail-logic.test.ts
- 精简过度枚举的 color-threshold.test.ts
- 新增 bunfig.toml 配置测试 preload
- 更新 DEVELOPMENT.md 测试章节
- 安装 @types/jsdom 修复类型声明

tests/web/components/TrendChart.test.tsx

@@ -0,0 +1,53 @@
+import "../../../tests/web/test-utils";
+import { render } from "@testing-library/react";
+import { describe, expect, test } from "bun:test";
+
+import type { TrendPoint } from "../../../src/shared/api";
+
+import { TrendChart } from "../../../src/web/components/TrendChart";
+
+describe("TrendChart", () => {
+  const data: TrendPoint[] = [
+    {
+      availability: 100,
+      avgDurationMs: 100,
+      bucketStart: "2025-01-15T10:00:00.000Z",
+      downChecks: 0,
+      maxDurationMs: 150,
+      minDurationMs: 50,
+      totalChecks: 10,
+      upChecks: 10,
+    },
+    {
+      availability: 95,
+      avgDurationMs: 120,
+      bucketStart: "2025-01-15T11:00:00.000Z",
+      downChecks: 1,
+      maxDurationMs: 200,
+      minDurationMs: 80,
+      totalChecks: 20,
+      upChecks: 19,
+    },
+  ];
+
+  test("有数据时不崩溃", () => {
+    const { container } = render(<TrendChart data={data} />);
+
+    expect(container.firstChild).not.toBeNull();
+  });
+
+  test("空数据显示占位", () => {
+    const { container } = render(<TrendChart data={[]} />);
+
+    // 应该显示占位文本
+    const element = container.querySelector(".trend-empty");
+    expect(element).not.toBeNull();
+  });
+
+  test("包含 trend-chart className", () => {
+    const { container } = render(<TrendChart data={data} />);
+
+    const element = container.querySelector(".trend-chart");
+    expect(element).not.toBeNull();
+  });
+});