feat: target 时间配置校验，interval 最小 10s，timeout 不大于 interval

在配置加载阶段新增通用 target 时间字段语义校验：
- interval 解析后不得小于 10s
- timeout 解析后不得大于同一 target 的 interval
- 默认值（30s / 10s）参与校验
- 变量引用先解析再校验
- 格式错误优先于关系错误，避免级联提示

src/server/checker/config-loader.ts

@@ -32,6 +32,8 @@ const DEFAULT_ROTATION_SIZE = "50MB";
 const DEFAULT_ROTATION_FREQUENCY: RotationFrequency = "daily";
 const DEFAULT_ROTATION_MAX_FILES = 14;
 
+const MINIMUM_INTERVAL_MS = parseDuration("10s");
+
 const VALID_LOG_LEVELS: LogLevel[] = ["trace", "debug", "info", "warn", "error", "fatal"];
 const VALID_ROTATION_FREQUENCIES: RotationFrequency[] = ["hourly", "daily", "weekly"];
 
@@ -208,6 +210,14 @@ function resolveTarget(
   return result;
 }
 
+function tryParseDuration(value: string): null | number {
+  try {
+    return parseDuration(value);
+  } catch {
+    return null;
+  }
+}
+
 function validateConfig(config: NormalizedProbeConfig): ConfigValidationIssue[] {
   const issues: ConfigValidationIssue[] = [];
   if (!Array.isArray(config.targets) || config.targets.length === 0) {
@@ -291,18 +301,21 @@ function validateConfig(config: NormalizedProbeConfig): ConfigValidationIssue[]
       : isString(targetIdValue)
         ? targetIdValue
         : undefined;
-    validateDurationValue(
-      isString(targetRecord["interval"]) ? targetRecord["interval"] : undefined,
-      `targets[${i}].interval`,
-      issues,
-      targetName,
-    );
-    validateDurationValue(
-      isString(targetRecord["timeout"]) ? targetRecord["timeout"] : undefined,
-      `targets[${i}].timeout`,
-      issues,
-      targetName,
-    );
+    const intervalRaw = isString(targetRecord["interval"]) ? targetRecord["interval"] : undefined;
+    const timeoutRaw = isString(targetRecord["timeout"]) ? targetRecord["timeout"] : undefined;
+    validateDurationValue(intervalRaw, `targets[${i}].interval`, issues, targetName);
+    validateDurationValue(timeoutRaw, `targets[${i}].timeout`, issues, targetName);
+
+    const intervalMs = tryParseDuration(intervalRaw ?? DEFAULT_INTERVAL);
+    const timeoutMs = tryParseDuration(timeoutRaw ?? DEFAULT_TIMEOUT);
+
+    if (intervalMs !== null && intervalMs < MINIMUM_INTERVAL_MS) {
+      issues.push(issue("invalid-value", `targets[${i}].interval`, "interval 不能小于 10s", targetName));
+    }
+
+    if (intervalMs !== null && timeoutMs !== null && timeoutMs > intervalMs) {
+      issues.push(issue("invalid-value", `targets[${i}].timeout`, "timeout 不能大于 interval", targetName));
+    }
   }
 
   return issues;