feat(11-02): add schedule:run as a scheduler process and a cron --once mode

- schedule:run runs a worker on the scheduled queue with every plugin's periodic jobs
- schedule:run --once runs entries due in the current app.timezone minute without River,
  warns and skips unregistered commands, and returns the first command error
- summer schedule:run delegate forwards --once
- tests for --once minute matching, forged-entry skipping (T-11-09) and ByPeriod dedupe

cmd/summer/main.go

@@ -6,9 +6,9 @@ import (
 	"os"
 	"strings"
 
-	"git.golem15.com/golem15/summercms/modules/bonfire"
 	"git.golem15.com/golem15/summercms/internal/build"
 	"git.golem15.com/golem15/summercms/internal/dev"
+	"git.golem15.com/golem15/summercms/modules/bonfire"
 )
 
 func main() {
@@ -43,6 +43,7 @@ func toolCommands() []bonfire.Command {
 		delegateCommand("migrate:status", "Show per-plugin migration history in the app binary"),
 		delegateCommand("serve", "Run the app HTTP server"),
 		delegateQueueWorkCommand(),
+		delegateScheduleRunCommand(),
 		delegateCommand("queue:clear", "Clear pending queued jobs in the app binary"),
 	}
 }