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

probe-config.schema.json

@@ -104,7 +104,7 @@
             "additionalProperties": false,
             "type": "object",
             "required": [
-              "name",
+              "id",
               "type",
               "http"
             ],
@@ -403,6 +403,10 @@
               "group": {
                 "type": "string"
               },
+              "id": {
+                "minLength": 1,
+                "type": "string"
+              },
               "interval": {
                 "type": "string"
               },
@@ -495,7 +499,7 @@
             "additionalProperties": false,
             "type": "object",
             "required": [
-              "name",
+              "id",
               "type",
               "cmd"
             ],
@@ -635,6 +639,10 @@
               "group": {
                 "type": "string"
               },
+              "id": {
+                "minLength": 1,
+                "type": "string"
+              },
               "interval": {
                 "type": "string"
               },
@@ -694,7 +702,7 @@
             "additionalProperties": false,
             "type": "object",
             "required": [
-              "name",
+              "id",
               "type",
               "db"
             ],
@@ -860,6 +868,10 @@
               "group": {
                 "type": "string"
               },
+              "id": {
+                "minLength": 1,
+                "type": "string"
+              },
               "interval": {
                 "type": "string"
               },
@@ -895,6 +907,24 @@
           }
         ]
       }
+    },
+    "variables": {
+      "type": "object",
+      "patternProperties": {
+        "^[a-zA-Z_][a-zA-Z0-9_]*$": {
+          "anyOf": [
+            {
+              "type": "string"
+            },
+            {
+              "type": "number"
+            },
+            {
+              "type": "boolean"
+            }
+          ]
+        }
+      }
     }
   },
   "$id": "https://dial.local/probe-config.schema.json",