Operator actions in the report reply (D1, R-314/R-279/R-177, decision 185)

The hub may ask the running controller for a CLOSED list of actions,
carried in the report ACK (operator_actions) and answered on the next
report (operator_action_results): offsite_backup_now, abandon_stop,
abandon_extend (1-30 days), run_job (fill-watch, offsite-integrity,
offsite-proof, disk-health-check). Unknown action/job/argument -> refused,
nothing called. Once per id (in memory; every action is safe to repeat).

- internal/report/opactions.go: the executor; results re-sent until the
  hub stops listing the id.
- scheduler.RunNow: refuses unknown / already-running jobs; OnDemand(ctx)
  makes an operator's offsite-integrity run even when not due.
- ExtendAbandon never shortens the countdown and refuses in the hub phase;
  StopAbandon reports failure when the hub cancel failed (it said success).
- Report ACK read cap 4 KiB -> 64 KiB (an ACK over the cap dropped every
  field in it).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/report/builder.go

@@ -173,6 +173,9 @@ func BuildReport(
 	// consume-once ACK-flag pattern (selftail.go). nil in the steady state.
 	r.ControllerLogTail = buildControllerLogTail(logger)
 
+	// Operator actions (decision 185): results the hub is still waiting for (opactions.go).
+	r.OperatorActionResults = pendingOperatorActionResults()
+
 	// Geo-restriction status — ALWAYS present (even when never configured) so the hub
 	// always renders the section. A nil pointer (omitempty) made the hub hide the whole
 	// section for a never-configured controller; a present-but-disabled report renders