Merge pull request 'fix(pr): pr +view 补齐 merged_at 字段' (#1) from fix/pr-view-merged-at into master

上游 #14 报告 pr +view 返回缺少 merged_at 字段(参照平台 API 文档)。
enrichPullRequestClosedAt 此前只从 journals 回填 closed_at,未处理
merged_at。本次从 pull_request.merged_at 提取并回填到顶层,对齐
已有 closed_at 的处理风格。

修复 #5

shortcuts/pr/pr.go

@@ -476,7 +476,17 @@ func enrichPullRequestClosedAt(ctx *common.RuntimeContext, env *output.Envelope)
 		return nil
 	}
 	pr, ok := data["pull_request"].(map[string]interface{})
-	if !ok || !isClosedPullRequest(pr) || stringField(pr, "closed_at") != "" {
+	if !ok {
+		return nil
+	}
+	// Backfill merged_at from the pull_request payload if missing. Issue #14
+	// reported that pr +view lacked merged_at even though the API docs expose it.
+	if mergedAt := stringField(pr, "merged_at"); mergedAt != "" {
+		if _, has := data["merged_at"]; !has {
+			data["merged_at"] = mergedAt
+		}
+	}
+	if !isClosedPullRequest(pr) || stringField(pr, "closed_at") != "" {
 		return nil
 	}
 	issue, ok := data["issue"].(map[string]interface{})