feat: tunnel TS exports, port forward labels, and db migrations

- Add TS derive and type annotations to all tunnel API param structs
- Export tunnel bindings to a tunnel/ subdirectory with index generation
- Change port forward label from String to Option<String>
- Add TunnelDatabase::init() with default subnet creation
- Add tunnel migration framework with m_00_port_forward_entry migration
  to convert legacy string-only port forwards to the new entry format

sdk/base/lib/osBindings/index.ts

@@ -306,3 +306,4 @@ export { WifiInfo } from './WifiInfo'
 export { WifiListInfo } from './WifiListInfo'
 export { WifiListOut } from './WifiListOut'
 export { WifiSsidParams } from './WifiSsidParams'
+export * as Tunnel from './tunnel'