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/templates/compose.yml.tmpl

@@ -13,7 +13,15 @@ services:
       org.label-schema.schema-version: "1.0"
       org.label-schema.vendor: dokku
 
+    {{- if $.VectorNetworks }}
+    networks:
+      bridge: {}
+      {{- range $name := $.VectorNetworks }}
+      {{ $name }}: {}
+      {{- end }}
+    {{- else }}
     network_mode: bridge
+    {{- end }}
 
     restart: unless-stopped
 
@@ -21,3 +29,15 @@ services:
       - "{{ $.DokkuLibRoot }}/data/logs:/etc/vector"
       - "/var/run/docker.sock:/var/run/docker.sock:ro"
       - "{{ $.DokkuLogsDir }}/apps:/var/log/dokku/apps"
+{{- if $.VectorNetworks }}
+
+networks:
+  bridge:
+    name: bridge
+    external: true
+  {{- range $name := $.VectorNetworks }}
+  {{ $name }}:
+    name: {{ $name }}
+    external: true
+  {{- end }}
+{{- end }}