fix(resume): recover cleanly after Pi exits

backend/src/app.ts

@@ -20,6 +20,7 @@ export interface BuildAppDeps {
   listModels?: ListModelsFn;
   getSettings?: () => Settings;
   readiness?: ReadinessManager;
+  hub?: SseHub;
 }
 
 export function buildApp(config: AppConfig, deps?: BuildAppDeps): FastifyInstance {
@@ -39,7 +40,7 @@ export function buildApp(config: AppConfig, deps?: BuildAppDeps): FastifyInstanc
     dataRoot: config.dataRoot,
   });
   const mgr = deps?.mgr ?? new PiProcessManager(config, deps?.spawnFn ? { spawnFn: deps.spawnFn } : undefined);
-  const hub = new SseHub();
+  const hub = deps?.hub ?? new SseHub();
   const readiness = deps?.readiness ?? new ReadinessManager(
     tht as ThtRunner,
     Math.round(config.ollamaEnsureTimeoutMs / 1000),