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/validate.test.ts

@@ -213,12 +213,12 @@ describe("validateUdpConfig", () => {
     expect(issues.some((i) => i.path.includes("responded") && i.message.includes("响应来源"))).toBe(true);
   });
 
-  it("reports invalid-type for negative expect.maxDurationMs", () => {
+  it("reports invalid-type for non-matcher expect.durationMs", () => {
     const issues = validateUdpConfig(
       makeInput({
         targets: [
           {
-            expect: { maxDurationMs: -100 },
+            expect: { durationMs: -100 },
             id: "test",
             type: "udp",
             udp: { host: "127.0.0.1", port: 53 },
@@ -226,7 +226,7 @@ describe("validateUdpConfig", () => {
         ],
       }),
     );
-    expect(issues.some((i) => i.code === "invalid-type" && i.path.includes("maxDurationMs"))).toBe(true);
+    expect(issues.some((i) => i.code === "invalid-type" && i.path.includes("durationMs"))).toBe(true);
   });
 
   it("reports invalid-type for non-boolean expect.responded", () => {