feat: 重构配置生命周期为 Authoring/Normalized/Resolved 三层

将变量替换和 expect 简写展开统一放入 Normalized 阶段，
运行时 AJV 使用 Normalized schema，导出 schema 面向 Authoring Config。

主要变更：
- 新增 normalizer.ts 实现 normalizeAuthoringConfig()
- 拆分 Authoring/Normalized 双 schema，checker 接口支持 authoring/normalized 片段
- config-loader 流程：normalize → Normalized AJV → semantic → resolve
- validator 兼容层自动分派 raw/normalized expect 形态
- 删除 rawExpect，store.expect 列写入 null
- Authoring schema 对 integer/boolean/enum 字段接受变量引用
- 修复 DB/HTTP validate 入口守卫和 LLM options integer 变量引用
- 优化 compact() 避免 undefined 覆盖隐患
- 移除 content.ts 恒为 true 的前置条件
- 同步 5 个主规范并归档 change

tests/server/checker/variables.test.ts

@@ -1,8 +1,35 @@
 import { describe, expect, test } from "bun:test";
 
+import { normalizeAuthoringConfig } from "../../../src/server/checker/normalizer";
 import { extractVariables, resolveVariables } from "../../../src/server/checker/variables";
 
 describe("config variables", () => {
+  test("normalizeAuthoringConfig 替换变量、展开 expect 简写并移除 variables", () => {
+    const result = normalizeAuthoringConfig({
+      targets: [
+        {
+          expect: { durationMs: "${maxMs}" },
+          http: { url: "${url}" },
+          id: "api",
+          type: "http",
+        },
+      ],
+      variables: { maxMs: 1000, url: "https://example.com" },
+    });
+
+    expect(result.issues).toHaveLength(0);
+    expect(result.config).toEqual({
+      targets: [
+        {
+          expect: { durationMs: { equals: 1000 } },
+          http: { url: "https://example.com" },
+          id: "api",
+          type: "http",
+        },
+      ],
+    });
+  });
+
   test("提取合法 variables 类型", () => {
     const result = extractVariables({ variables: { enabled: true, host: "example.com", port: 5432 } });