feat: 新增 LLM checker 支持大模型服务应用层拨测

基于 AI SDK v6 实现 openai/openai-responses/anthropic 三类 provider 的 http/stream 模式调用
支持 output/finishReason/usage/stream 等完整 expect 断言链路
新增 9 个源文件和 5 个测试文件共 78 个测试
更新 README/DEVELOPMENT/probes.example.yaml 和 probe-config.schema.json

tests/server/checker/runner/llm/registry.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, test } from "bun:test";
+
+import { checkerRegistry } from "../../../../../src/server/checker/runner";
+
+describe("LLM registry integration", () => {
+  test("registry 包含 llm 类型", () => {
+    expect(checkerRegistry.supportedTypes).toContain("llm");
+  });
+
+  test("llm checker 可获取", () => {
+    const checker = checkerRegistry.tryGet("llm");
+    expect(checker).toBeDefined();
+    expect(checker!.type).toBe("llm");
+    expect(checker!.configKey).toBe("llm");
+  });
+
+  test("llm checker schemas 有效", () => {
+    const checker = checkerRegistry.get("llm");
+    expect(checker.schemas.config).toBeDefined();
+    expect(checker.schemas.defaults).toBeDefined();
+    expect(checker.schemas.expect).toBeDefined();
+  });
+
+  test("llm checker validate 方法可用", () => {
+    const checker = checkerRegistry.get("llm");
+    const issues = checker.validate({
+      defaults: {},
+      targets: [],
+    });
+    expect(issues).toHaveLength(0);
+  });
+});