Preserve opened subagents when parents are archived (#3279)

* fix(subagents): preserve opened children on parent archive

Opening a managed child represents user ownership only while that client's tab remains open. Track that intent per client, detach surviving children during parent archive, and keep single and bulk tab-close behavior consistent.

* fix(subagents): mark generic tab openings

Centralize managed child tab ownership in agent navigation so list, command-center, deep-link, notification, and subagent-track openings all mark ownership before creating the tab. Use stable localized errors for lifecycle failures.

* fix(subagents): classify cold tab openings

Fetch uncached agents before deciding whether tab ownership must be recorded, so notification, desktop, and cold-route openings cannot bypass parent archive protection.

* fix(app): translate navigation fallback errors

* fix(navigation): allow offline workspace intents

* refactor(app): derive subagent ownership from open tabs

* fix(server): serialize subagent lifecycle ownership

packages/app/src/i18n/resources/ja.ts

@@ -619,6 +619,7 @@ export const ja: TranslationResources = {
         reloadingAgent: "エージェントを再読み込み中...",
         reloadedAgent: "エージェントを再読み込みしました",
         failedToReloadAgent: "エージェントの再読み込みに失敗しました",
+        failedToCloseAgent: "エージェントを閉じられませんでした",
       },
       confirmations: {
         unsavedTitle: "未保存の変更",