Handle SvelteKit adapters properly

• with SvelteKit using bun as the package manager and builder does not mean to use bun as the runner
• the runner language is determined by the adapter, not the runtime used to build
• I can use bun to build a nodejs output, and vice versa
• and also: with adapter-static, it should use the nginx thing it does for astro

Stories:

• Right now, if I launch a SvelteKit app that uses bun as its package manager but adapter-node as its runtime, it tries to run the node bundle with bun which won't work properly
• Right now, if I launch a SvelteKit app that uses adapter-static, it assumes it's node/bun and runs it with that
• Right now, the deno adapter and anything else probably is broken in a similar way

まず、生成されたアプリケーションの起動時に使用される SvelteKit のアダプターとランタイム検出を追跡し、静的出力に対する既存の Astro の nginx 処理と比較します。完了条件は、adapter-node がパッケージマネージャーや builder に関係なく Node を使用し、adapter-static が nginx を使用し、他のアダプターが誤って Bun や Node で実行されないことです。