feat(apiserver): surface human-readable job ID (fmt_jobid form) in responses

The MCP/apiserver returned the raw 64-bit job ID (e.g. 73930964699447296)
while xce_test/xcecli display the dash form (e.g. 1-0-1786585485-0) that
parse_jobid accepts. A user taking the numeric form into xce_test fails to
parse it. The apiserver is the data-correctness owner (MCP only reads), so
it now emits the controller's fmt_jobid form alongside the numeric ID:

- models: JobSubmitResponse gains job_id_human; job list rows gain
  job_id_human (processJobData), using the existing backend.FormatJobID.
- schedulerclient: URMJob.HumanID + SubmitJobResult.JobIDHuman parse it.
- Tests: backend.FormatJobID (real t1 job, pre-cluster1 job, array child);
  processJobData adds job_id_human.

Also rename the SSE permission event:subscribe → event:view so mcp_readonly
stays strictly *:view (the read-only invariant test enforces).

Verified live on t1: scheduler_submit returns job_id_human 1-0-1786586474-0
and scheduler_get_job returns human_id.

Co-Authored-By: Claude <noreply@anthropic.com>

src/frontend/apiserver/backend/convert_test.go

@@ -916,3 +916,44 @@ func TestResolveExecUser(t *testing.T) {
 		})
 	}
 }
+
+func TestFormatJobID(t *testing.T) {
+	tests := []struct {
+		name  string
+		jobID int64
+		want  string
+	}{
+		{
+			name:  "real job from t1",
+			jobID: 73930964699447296, // cluster=1 apiserver=0 ts=1786585485 seq=0
+			want:  "1-0-1786585485-0",
+		},
+		{
+			name: "pre-cluster1 job",
+			// cluster=0 apiserver=7 ts=1786416651 seq=138313
+			jobID: int64(uint64(0)<<56 | uint64(7)<<52 | uint64(1786416651)<<20 | uint64(138313)),
+			want:  "0-7-1786416651-138313",
+		},
+		{
+			name:  "zero",
+			jobID: 0,
+			want:  "0-0-0-0",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := FormatJobID(tt.jobID); got != tt.want {
+				t.Errorf("FormatJobID(%d) = %q, want %q", tt.jobID, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestFormatJobID_ArrayChild(t *testing.T) {
+	// Array child: tag 0x01 set, seq split into arrayjob(high)<<15 and idx(low).
+	// cluster=1 apiserver=0 ts=1786585485, arrayjob=3<<15, idx=5.
+	jobID := int64(uint64(1)<<56 | uint64(0)<<52 | uint64(1786585485)<<20 | uint64(0x01)<<62 | uint64(3)<<15 | uint64(5))
+	if got, want := FormatJobID(jobID), "1-0-1786585485-98304[5]"; got != want {
+		t.Errorf("FormatJobID(array) = %q, want %q", got, want)
+	}
+}