Issue 17: StartOS 0.4.0 packaging

- Dockerfile: multi-stage build (Node frontend + Python backend)
- StartOS manifest, interfaces, backups, version graph
- start.sh: auto-generates session secret, creates first approver on boot
- Backend serves built frontend as SPA in production
- Single data volume for SQLite DB, platform backups cover it

deploy/startos/sdk.ts

@@ -0,0 +1,4 @@
+import { StartSdk } from '@start9labs/start-sdk'
+import { manifest } from './manifest'
+
+export const sdk = StartSdk.of().withManifest(manifest).build(true)