feat: archive sessions from the mobile session row

Add a two-step archive affordance to each mobile session row, mirroring the
project remove confirmation: tapping the archive icon arms an inline confirm
(with cancel), and confirming archives the session. Only one row can be in
the confirming state at a time.

Also relabel the project remove confirmation from "Delete" to "Close"
across all locales, since removing a project closes it from the app rather
than deleting anything.

packages/ui/src/lib/i18n/messages/zh-TW.ts

@@ -64,9 +64,11 @@ export const dict: Record<I18nKey, string> = {
   'mobile.sessions.moveDownAria': '將 {label} 下移',
   'mobile.sessions.removeProjectAria': '移除 {label}',
   'mobile.sessions.cancelRemoveProjectAria': '取消移除 {label}',
-  'mobile.sessions.confirmRemoveProject': '刪除',
+  'mobile.sessions.confirmRemoveProject': '關閉',
   'mobile.sessions.confirmRemoveProjectAria': '確認移除 {label}',
   'mobile.sessions.toast.projectRemoved': '已移除 {label}',
+  'mobile.sessions.archiveSessionAria': '封存 {title}',
+  'mobile.sessions.cancelArchiveAria': '取消封存 {title}',
   'mobile.sessions.editProjectAria': '編輯 {label}',
   'mobile.projectEdit.worktreesTitle': '工作樹',
   'mobile.projectEdit.worktreesEmpty': '此專案還沒有工作樹。',