feat: 配置变量系统与 target id/name 双字段标识

- 新增顶层 variables 段支持 string/number/boolean 字面量
- target 字符串字段支持 、、{...} 转义语法
- 变量解析优先级: variables -> process.env -> 默认值 -> 报错
- 完整引用保留原始类型，部分引用拼接为字符串
- 变量替换在 YAML 解析后、AJV 校验前执行
- 替换仅作用于 targets，跳过 id/type 字段
- target 新增必填 id 字段作为唯一标识，name 改为可选展示名称
- 数据库存储/API/前端全面迁移到 id 标识
- 统一 checker 运行时类型检查为 es-toolkit predicates
- 同步 delta specs 到主 specs，归档 config-variables 变更

tests/server/checker/engine.test.ts

@@ -15,8 +15,7 @@ const processEnv = Object.fromEntries(
 );
 
 function createMockStore(targetNames: string[]) {
-  let nextId = 1;
-  const targets = targetNames.map((name) => ({ id: nextId++, name }));
+  const targets = targetNames.map((name) => ({ id: name, name }));
   const results: Array<Record<string, unknown>> = [];
 
   return {
@@ -57,6 +56,7 @@ function makeCommandTarget(name: string, overrides?: Partial<ResolvedCommandTarg
       maxOutputBytes: 1024 * 1024,
     },
     group: "default",
+    id: name,
     intervalMs: 60000,
     name,
     timeoutMs: 5000,
@@ -177,7 +177,7 @@ describe("ProbeEngine", () => {
 
       const results = (mockStore as unknown as { _results: Array<Record<string, unknown>> })._results;
       expect(results.length).toBe(2);
-      expect(results[0]!["targetId"]).toBe(1);
+      expect(results[0]!["targetId"]).toBe("reject-cmd");
       expect(results[0]!["matched"]).toBe(false);
       expect(results[0]!["durationMs"]).toBeNull();
       expect(results[0]!["statusDetail"]).toBeNull();
@@ -188,7 +188,7 @@ describe("ProbeEngine", () => {
         phase: "internal",
       });
       expect(typeof results[0]!["timestamp"]).toBe("string");
-      expect(results[1]!["targetId"]).toBe(2);
+      expect(results[1]!["targetId"]).toBe("good-cmd");
       expect(results[1]!["matched"]).toBe(true);
     } finally {
       checker.execute = originalExecute;
@@ -235,7 +235,7 @@ describe("ProbeEngine", () => {
     expect(true).toBe(true);
   });
 
-  test("未注册的 targetName 不写入结果", async () => {
+  test("未注册的 target id 不写入结果", async () => {
     const target = makeCommandTarget("unknown-target");
     const mockStore = createMockStore(["other-name"]) as unknown as ProbeStore;
     const engine = new ProbeEngine(mockStore, [target]);
@@ -268,6 +268,7 @@ describe("ProbeEngine", () => {
           method: "GET",
           url: `http://localhost:${httpServer.port}/`,
         },
+        id: "http-test",
         intervalMs: 60000,
         name: "http-test",
         timeoutMs: 5000,