feat: 扩展配置变量替换范围至 server/probes/targets，支持空默认值语法

src/server/checker/variables.ts

@@ -63,14 +63,8 @@ export function resolveVariables(config: unknown): { config: unknown; issues: Co
   if (!isPlainObject(config)) {
     return { config, issues };
   }
-  const configRecord = config as Record<string, unknown>;
-  const rawTargets: unknown = configRecord["targets"];
-  if (!Array.isArray(rawTargets)) {
-    return { config, issues };
-  }
 
-  const targets = rawTargets.map((target, index) => resolveTargetVariables(target, index, variables, issues));
-  return { config: { ...config, targets }, issues };
+  return { config: resolveConfigValue(config, "", variables, issues), issues };
 }
 
 function describeInvalidVariableValue(value: unknown): string {
@@ -80,6 +74,7 @@ function describeInvalidVariableValue(value: unknown): string {
 }
 
 function inferStringValue(value: string): VariableValue {
+  if (value === "") return value;
   const numberValue = Number(value);
   if (Number.isFinite(numberValue)) return numberValue;
   if (value === "true") return true;
@@ -126,6 +121,31 @@ function replaceStringValue(
   return escaped.reduce((result, literal, index) => result.replace(`\u0000${index}\u0000`, literal), replaced);
 }
 
+function resolveConfigValue(
+  value: unknown,
+  path: string,
+  variables: Map<string, VariableValue>,
+  issues: ConfigValidationIssue[],
+): unknown {
+  if (!isPlainObject(value)) return value;
+
+  const result: Record<string, unknown> = {};
+  for (const [key, item] of Object.entries(value)) {
+    const itemPath = joinPath(path, key);
+    if (key === "variables") {
+      result[key] = item;
+      continue;
+    }
+    if (key === "targets" && Array.isArray(item)) {
+      result[key] = item.map((target, index) => resolveTargetVariables(target, index, variables, issues));
+      continue;
+    }
+    result[key] =
+      key === "server" || key === "probes" ? resolveValue(item, itemPath, variables, issues, { path: itemPath }) : item;
+  }
+  return result;
+}
+
 function resolveTargetVariables(
   target: unknown,
   index: number,
@@ -165,10 +185,9 @@ function resolveValue(
   const result: Record<string, unknown> = {};
   for (const [key, item] of Object.entries(value)) {
     const itemPath = joinPath(path, key);
-    result[key] =
-      key === "id" || key === "type"
-        ? item
-        : resolveValue(item, itemPath, variables, issues, { ...context, path: itemPath });
+    result[key] = shouldSkipVariableResolution(itemPath)
+      ? item
+      : resolveValue(item, itemPath, variables, issues, { ...context, path: itemPath });
   }
   return result;
 }
@@ -202,3 +221,7 @@ function resolveVariableReference(
   );
   return undefined;
 }
+
+function shouldSkipVariableResolution(path: string): boolean {
+  return /^targets\[\d+\]\.(?:id|type)$/.test(path);
+}