refactor: move restart field from ServerInfo to ServerStatus

The restart reason belongs with other server state (shutting_down,
restarting, update_progress) rather than on the top-level ServerInfo.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

sdk/base/lib/osBindings/ServerStatus.ts

@@ -2,10 +2,12 @@
 import type { BackupProgress } from './BackupProgress'
 import type { FullProgress } from './FullProgress'
 import type { PackageId } from './PackageId'
+import type { RestartReason } from './RestartReason'
 
 export type ServerStatus = {
   backupProgress: { [key: PackageId]: BackupProgress } | null
   updateProgress: FullProgress | null
   shuttingDown: boolean
   restarting: boolean
+  restart: RestartReason | null
 }