feat: attach vector container to additional docker networks

Adds a new global `vector-networks` property on the logs plugin that takes a comma-separated list of Docker networks. When set, the rendered compose file declares each network plus `bridge` as external and joins them on the vector service, so `docker compose up` reconciles attachments on every `logs:vector-start`. When unset, the existing `network_mode: bridge` template is preserved unchanged. The value is validated against `docker network inspect` at set time, rejects the reserved `bridge` entry, and is surfaced in `dokku logs:report` via `--logs-vector-global-networks`.

plugins/logs/report.go

@@ -24,6 +24,7 @@ func ReportSingleApp(appName string, format string, infoFlag string) error {
 			"--logs-global-max-size":        reportGlobalMaxSize,
 			"--logs-global-vector-sink":     reportGlobalVectorSink,
 			"--logs-vector-global-image":    reportVectorGlobalImage,
+			"--logs-vector-global-networks": reportVectorGlobalNetworks,
 		}
 	} else {
 		flags = map[string]common.ReportFunc{
@@ -35,6 +36,7 @@ func ReportSingleApp(appName string, format string, infoFlag string) error {
 			"--logs-app-label-alias":          reportAppLabelAlias,
 			"--logs-max-size":                 reportMaxSize,
 			"--logs-vector-global-image":      reportVectorGlobalImage,
+			"--logs-vector-global-networks":   reportVectorGlobalNetworks,
 			"--logs-vector-sink":              reportVectorSink,
 		}
 	}
@@ -84,6 +86,10 @@ func reportVectorGlobalImage(appName string) string {
 	return getComputedVectorImage()
 }
 
+func reportVectorGlobalNetworks(appName string) string {
+	return common.PropertyGet("logs", "--global", "vector-networks")
+}
+
 func reportGlobalVectorSink(appName string) string {
 	value := common.PropertyGet("logs", "--global", "vector-sink")
 	if value == "" {