hpc status: detail rendering only inspects first task of array / het jobs

[ultimatile]

Summary

hpc status <id> on an array job or a heterogeneous job reports the
accounting fields of the first parent row only.
The polling path fixed in #10 already aggregates across rows, so
hpc submit --wait correctly waits until every task is terminal —
but the new detail path added in #5 has no equivalent treatment.

Reproduction

For an array job whose tasks finish with mixed outcomes (e.g. one OOM,
two COMPLETED), the user sees:

Job 12345_0: COMPLETED
  ExitCode: 0:0
  Elapsed:  00:01:23
  MaxRSS:   1024K
  ReqMem:   16Gn

…with no indication that another task was OUT_OF_MEMORY.
Same shape for hetjob leaders: only the first component's accounting
is rendered.

Proposal

Render either:

1. one block per task / het component (probably gated by an opt-in flag
   to avoid noise on large arrays), with the parent row identified by
   the canonical JobID (e.g. 12345_0, 12345_1 for array tasks;
   12345+0, 12345+1 for het components), or
2. an aggregate summary line (e.g. 3 tasks: 2 COMPLETED, 1 OUT_OF_MEMORY)
   with per-task drill-down on demand.

The exact UX shape is part of this issue.

Out of scope

• Changes to the polling / wait_for_job path (already handled in fix(scheduler): aggregate Slurm sacct rows for array job wait #10).
• PJM array-equivalent rendering — see the companion PJM-detail issue.