A build module takes asks only within its node's build hours

The operator, 2026-10-26 21:18: g14 builds only from 18:00 to 06:00. A build-hours setting names a
window per node in its local time (crossing midnight allowed, absent = any hour); outside it the
capacity judged by is 0, running steps finish, and the puller wakes on one timer at the next edge.
The change is said in the log and in capacity.<node> with the window and when it opens.

go/delivery/stepasks.go

@@ -724,6 +724,12 @@ type Capacity struct {
 	// when no quota is known.
 	CoresPerStep float64 `json:"cores-per-step"`
 	ByCPU        int     `json:"by-cpu,omitempty"`
+	// BuildHours is the node's build window (HH:MM-HH:MM, its local time and zone), absent when it builds at any hour;
+	// OutsideHours says the time judged fell outside it, so Effective is 0 and the next step waits for the window to open.
+	BuildHours   string `json:"build-hours,omitempty"`
+	OutsideHours bool   `json:"outside-hours,omitempty"`
+	// BuildHoursFault is why the node's build-hours value cannot be read, naming the value: it then builds at any hour.
+	BuildHoursFault string `json:"build-hours-fault,omitempty"`
 	// Why is the capacity in words: what bounds it.
 	Why string    `json:"why"`
 	At  time.Time `json:"at,omitzero"`