feat: 新增本机 CPU checker

- 新增 type: cpu checker，基于 os.cpus() 两次快照计算 CPU 使用率
- 配置项：sampleDuration（默认 1s）、includePerCore（默认 false）
- expect 字段：usagePercent、idlePercent、maxCoreUsagePercent、minCoreUsagePercent、durationMs
- idlePercent 与 usagePercent 互补恒等于 100，百分比范围 0-100
- logicalCoreCount 仅输出到 observation，不作为 expect 字段
- 不暴露 userPercent / systemPercent
- 语义校验禁止 sampleDuration >= timeout
- 支持 AbortSignal 超时取消
- 完整测试覆盖：schema、validate、normalize、resolve、calculate、execute、expect、config-loader
- 新增用户文档 docs/user/checkers/cpu.md
- 更新 checker 索引、配置类型列表、示例配置和 schema

tests/server/checker/runner/cpu/schema.test.ts

@@ -0,0 +1,77 @@
+import Ajv from "ajv";
+import { describe, expect, test } from "bun:test";
+
+import { cpuCheckerSchemas } from "../../../../../src/server/checker/runner/cpu/schema";
+
+const ajv = new Ajv({ strict: false });
+
+describe("CPU checker schema", () => {
+  test("authoring config 允许变量引用", () => {
+    const validate = ajv.compile(cpuCheckerSchemas.authoring.config);
+    expect(validate({ includePerCore: "${per_core|false}", sampleDuration: "${sample_dur|1s}" })).toBe(true);
+  });
+
+  test("normalized config 允许合法值", () => {
+    const validate = ajv.compile(cpuCheckerSchemas.normalized.config);
+    expect(validate({ includePerCore: true, sampleDuration: "1s" })).toBe(true);
+  });
+
+  test("normalized config 空配置通过", () => {
+    const validate = ajv.compile(cpuCheckerSchemas.normalized.config);
+    expect(validate({})).toBe(true);
+  });
+
+  test("config 拒绝额外字段", () => {
+    const validate = ajv.compile(cpuCheckerSchemas.authoring.config);
+    expect(validate({ extraField: true })).toBe(false);
+  });
+
+  test("authoring expect 允许 ValueMatcher 简写", () => {
+    const validate = ajv.compile(cpuCheckerSchemas.authoring.expect);
+    expect(validate({ usagePercent: 85 })).toBe(true);
+    expect(validate({ usagePercent: { lte: 85 } })).toBe(true);
+  });
+
+  test("normalized expect 允许 matcher 对象", () => {
+    const validate = ajv.compile(cpuCheckerSchemas.normalized.expect);
+    expect(validate({ idlePercent: { gte: 15 }, usagePercent: { lte: 85 } })).toBe(true);
+  });
+
+  test("expect 拒绝 logicalCoreCount 字段", () => {
+    const validate = ajv.compile(cpuCheckerSchemas.authoring.expect);
+    expect(validate({ logicalCoreCount: { gte: 4 } })).toBe(false);
+  });
+
+  test("expect 拒绝 userPercent 字段", () => {
+    const validate = ajv.compile(cpuCheckerSchemas.authoring.expect);
+    expect(validate({ userPercent: { lte: 50 } })).toBe(false);
+  });
+
+  test("expect 拒绝 systemPercent 字段", () => {
+    const validate = ajv.compile(cpuCheckerSchemas.authoring.expect);
+    expect(validate({ systemPercent: { lte: 50 } })).toBe(false);
+  });
+
+  test("expect 允许所有合法字段", () => {
+    const validate = ajv.compile(cpuCheckerSchemas.normalized.expect);
+    expect(
+      validate({
+        durationMs: { lte: 2000 },
+        idlePercent: { gte: 15 },
+        maxCoreUsagePercent: { lte: 95 },
+        minCoreUsagePercent: { gte: 0 },
+        usagePercent: { lte: 85 },
+      }),
+    ).toBe(true);
+  });
+
+  test("expect 拒绝额外字段", () => {
+    const validate = ajv.compile(cpuCheckerSchemas.normalized.expect);
+    expect(validate({ unknownField: 1 })).toBe(false);
+  });
+
+  test("expect 空对象通过", () => {
+    const validate = ajv.compile(cpuCheckerSchemas.normalized.expect);
+    expect(validate({})).toBe(true);
+  });
+});