feat(service): add pagination to GetJobs endpoint

GetJobs now accepts page/page_size query parameters and returns JobListResponse instead of raw array. Uses in-memory pagination matching GetJobHistory pattern.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

internal/model/job.go

@@ -66,6 +66,12 @@ type JobListResponse struct {
 	PageSize int           `json:"page_size"` // 每页条数
 }
 
+// JobListQuery contains pagination parameters for active job listing.
+type JobListQuery struct {
+	Page     int `form:"page,default=1" json:"page,omitempty"`            // 页码 (从 1 开始)
+	PageSize int `form:"page_size,default=20" json:"page_size,omitempty"` // 每页条数
+}
+
 // JobHistoryQuery contains query parameters for job history.
 type JobHistoryQuery struct {
 	Users       string `form:"users" json:"users,omitempty"`                    // 按用户名过滤 (逗号分隔)