feat(job-array-one-based-index): xcecli submit shows the array (task 8.3)

Submitting an array prints the server's message with the array ID in
written form (no [k]) and the element count, e.g.
'Job <0-0-...> is submitted to queue <normal> (3 elements).'; ordinary
submits print exactly as before. The client model mirrors array_size.
Submit help documents name[1-N] and name[1], numbering from 1 and the
API-server limit (default 1000, at most 32767).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/frontend/xcecli/models/jobs.go

@@ -365,6 +365,9 @@ type JobSubmitRequest struct {
 type JobSubmitData struct {
 	JobID   int64  `json:"jobid"`
 	Message string `json:"message"`
+	// ArraySize is the number of elements of a submitted array (3.2); zero
+	// for an ordinary job. The printed count comes from Message.
+	ArraySize int `json:"array_size,omitempty"`
 }
 
 // JobSubmitResponse define the data structure in the job submit response