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_test.go

@@ -19,7 +19,7 @@ func TestToolCommandNames(t *testing.T) {
 	for _, c := range toolCommands() {
 		names = append(names, c.Name)
 	}
-	for _, want := range []string{"build", "make:plugin", "make:model", "make:migration", "make:command", "make:job", "make:admin-controller", "plugin:add", "dev", "migrate", "migrate:rollback", "migrate:status", "serve", "queue:work", "queue:clear"} {
+	for _, want := range []string{"build", "make:plugin", "make:model", "make:migration", "make:command", "make:job", "make:admin-controller", "plugin:add", "dev", "migrate", "migrate:rollback", "migrate:status", "serve", "queue:work", "queue:clear", "schedule:run"} {
 		if !slices.Contains(names, want) {
 			t.Fatalf("missing %s in %v", want, names)
 		}
@@ -32,6 +32,7 @@ func TestToolCommandNames(t *testing.T) {
 		"make:command":          {"[plugin] [name]"},
 		"make:job":              {"[plugin] [name]"},
 		"make:admin-controller": {"[plugin] [name]"},
+		"schedule:run":          {"--once"},
 	}
 	for cmd, wants := range helpWants {
 		var buf bytes.Buffer