feat: add service volume contracts

ts/data/service.ts

@@ -1,6 +1,22 @@
 import type { IServiceRessources } from './docker.js';
 import type { IRegistryTarget } from './registry.js';
 
+export interface IServiceVolume {
+  /** Stable Docker volume name. If omitted, Coreflow derives one from service id and mount path. */
+  name?: string;
+  /** Alias for name when a volume is shared intentionally across services. */
+  source?: string;
+  /** Container path where the volume is mounted. */
+  mountPath: string;
+  /** Docker volume driver. Defaults to corestore. */
+  driver?: 'corestore' | 'local' | string;
+  readOnly?: boolean;
+  /** Whether backup orchestration should snapshot this volume. Defaults to true. */
+  backup?: boolean;
+  /** Driver-specific options forwarded to Docker's VolumeDriver.Create request. */
+  options?: Record<string, string>;
+}
+
 export interface IService {
   id: string;
   data: {
@@ -55,6 +71,7 @@ export interface IService {
       web: number;
       custom?: { [domain: string]: string };
     };
+    volumes?: IServiceVolume[];
     resources?: IServiceRessources;
     domains: {
       /**