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/AddPackageSignerParams.ts

@@ -6,5 +6,5 @@ export type AddPackageSignerParams = {
   id: PackageId
   signer: Guid
   versions: string | null
-  merge?: boolean
+  merge: boolean
 }