refactor: 引入 Checker 统一接口与 Runner 抽象机制

定义 Checker 接口（resolve/execute/serialize）和 CheckerRegistry
注册中心，消除 engine/config-loader/store 中硬编码类型分支。
按 checker 类型分子包（runner/http/、runner/command/），提取
共享 expect 到 runner/shared/。超时控制通过引擎注入 AbortSignal。
CheckFailure.phase 从联合类型改为 string。配置校验下沉到各
Checker.resolve() 内部。

新增 checker-runner-abstraction spec，更新 DEVELOPMENT.md。

tests/server/checker/runner/shared/text.test.ts

@@ -0,0 +1,45 @@
+import { describe, expect, test } from "bun:test";
+import { checkTextRules } from "../../../../../src/server/checker/runner/shared/text";
+
+describe("checkTextRules", () => {
+  test("无规则返回匹配成功", () => {
+    const r = checkTextRules("hello", [], "stdout");
+    expect(r.matched).toBe(true);
+    expect(r.failure).toBeNull();
+  });
+
+  test("单条 contains 规则匹配成功", () => {
+    const r = checkTextRules("build completed successfully", [{ contains: "completed" }], "stdout");
+    expect(r.matched).toBe(true);
+  });
+
+  test("单条 contains 规则匹配失败", () => {
+    const r = checkTextRules("build completed successfully", [{ contains: "failed" }], "stdout");
+    expect(r.matched).toBe(false);
+    expect(r.failure!.phase).toBe("stdout");
+    expect(r.failure!.path).toBe("stdout[0]");
+  });
+
+  test("多条规则全部通过", () => {
+    const r = checkTextRules("version: 3.2.1, build: ok", [{ contains: "version" }, { match: "\\d+\\.\\d+\\.\\d+" }], "stdout");
+    expect(r.matched).toBe(true);
+  });
+
+  test("第一条规则失败立即返回", () => {
+    const r = checkTextRules("error occurred", [{ contains: "success" }, { contains: "error" }], "stdout");
+    expect(r.matched).toBe(false);
+    expect(r.failure!.phase).toBe("stdout");
+    expect(r.failure!.path).toBe("stdout[0]");
+  });
+
+  test("stderr phase", () => {
+    const r = checkTextRules("warning: deprecated", [{ contains: "warning" }], "stderr");
+    expect(r.matched).toBe(true);
+    expect(r.failure).toBeNull();
+  });
+
+  test("empty 操作符", () => {
+    const r = checkTextRules("", [{ empty: true }], "stderr");
+    expect(r.matched).toBe(true);
+  });
+});