refactor: 统一 expect 断言体系，引入共享 ValueMatcher/ContentRules/KeyValueExpect 模型

- 引入共享 ValueMatcher（equals/contains/regex/exists/empty/gt/gte/lt/lte）
- 引入共享 ContentRules 数组（direct/json/css/xpath 提取器）
- 引入共享 KeyValueExpect（动态键值断言，字面量等价 equals）
- maxDurationMs → durationMs: ValueMatcher（所有 checker）
- match → regex（固定无 flags）
- Ping max* → packetLossPercent/avgLatencyMs/maxLatencyMs（ValueMatcher）
- LLM finishReason/rawFinishReason → ValueMatcher
- DB 新增 result: ContentRules
- TCP banner → ContentRules 数组
- 删除旧模块：operator.ts、validate-operator.ts、duration.ts、body.ts、text.ts、output.ts
- 更新全部 checker schema/validate/expect/execute
- 更新 probe-config.schema.json、probes.example.yaml
- 更新 README.md、DEVELOPMENT.md（含 expect 字段选择规范）
- 同步 10 个 delta specs 到主 specs，归档 change

tests/server/checker/runner/udp/expect.test.ts

@@ -76,13 +76,13 @@ describe("checkResponseText", () => {
   });
 
   it("多条规则全部匹配", () => {
-    const result = checkResponseText("hello world", [{ contains: "hello" }, { match: "^hello" }]);
+    const result = checkResponseText("hello world", [{ contains: "hello" }, { regex: "^hello" }]);
     expect(result.matched).toBe(true);
     expect(result.failure).toBeNull();
   });
 
   it("多条规则第二条失败 → 不匹配", () => {
-    const result = checkResponseText("hello world", [{ contains: "hello" }, { match: "^world" }]);
+    const result = checkResponseText("hello world", [{ contains: "hello" }, { regex: "^world" }]);
     expect(result.matched).toBe(false);
     expect(result.failure!.phase).toBe("response");
     expect(result.failure!.path).toBe("response[1]");