docs(plans): correct S22's trigger-kind and registration counts

What this corrects

S22 defines four trigger:* kinds: trigger:counter_drain_repo and trigger:counter_drain_namespace in Step 10, trigger:reconciliation and trigger:reconciliation_orphan_sweep in Step 15.

!1442 (merged) added the orphan sweep and rewrote the Step 15 entry to four registrations. Three lines elsewhere in the plan kept the earlier three-kind shape.

Line	Was	Is
59	three trigger:* kinds; four registrations in Step 10 and two in Step 15	four kinds; four and four
1004	"Not the third periodic kind: trigger:reconciliation's arg type is Step 15's"	names both Step 15 kinds
1382	ReconciliationTriggerArgs alone against reconcile_trigger.go	adds ReconciliationOrphanSweepTriggerArgs

How the corrected values were derived

internal/accounting/register.go on main makes two RegisterPeriodic and two RegisterWorker calls for the two reconciliation kinds, so Step 15 makes four registrations. The plan's own Step 15 entry already says "four registrations for the two periodic kinds inside RegisterRiverJobs", so line 59 contradicted it.

Both reconciliation arg types live in internal/accounting/reconcile_trigger.go, and their Kind() methods return trigger:reconciliation and trigger:reconciliation_orphan_sweep.

Why this is not part of !1803 (merged)

Step MRs do not edit the plan file, and the Research Findings section is write-once from a step branch. !1803 (merged) records the drift in its own description and cannot correct it.

!1803 (merged)'s description names lines "59, 1004 and 1381". The third stale line is 1382; 1381 is an unrelated composition-root-rename row. That description is corrected in the same round.

The last standing S22 docs(plans) MR, !1809 (merged), merged carrying Status rows only, so no open MR was left to take these lines.