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/shared/duration.test.ts

@@ -1,6 +1,13 @@
 import { describe, expect, test } from "bun:test";
 
-import { checkDuration } from "../../../../../src/server/checker/expect/duration";
+import { checkValueMatcher } from "../../../../../src/server/checker/expect/matcher";
+
+function checkDuration(durationMs: number, maxDurationMs?: number) {
+  return checkValueMatcher(durationMs, maxDurationMs === undefined ? undefined : { lte: maxDurationMs }, {
+    path: "durationMs",
+    phase: "duration",
+  });
+}
 
 describe("checkDuration", () => {
   test("未配置 maxDurationMs 返回匹配成功", () => {