fix(servers): retain cloud instances awaiting IPs

Persist DigitalOcean, Hetzner, and Vultr servers before public IP
assignment, then backfill placeholder addresses from provider state.

Treat partial Sentinel snapshots as non-authoritative and document the
destinations API with OpenAPI schemas.

database/migrations/2026_07_08_105014_add_uuid_to_cloud_init_scripts_table.php

@@ -15,7 +15,7 @@ return new class extends Migration
 
         DB::table('cloud_init_scripts')
             ->whereNull('uuid')
-            ->orderBy('id')
+            ->lazyById()
             ->each(function (object $script): void {
                 DB::table('cloud_init_scripts')
                     ->where('id', $script->id)