Server AI usage on the account card, clearer guest lifetime, folder share improvements

[tim4431]

• The account card shows what the account spent through the server's shared AI connections in the last 24 h (a bar under the admin's limit, the plain count without one); the allowance object is now reported whenever a shared entry applies, limit 0 = unlimited.
• Guest lifetime wording: "Temporary workspace · deleted in N hours", the hint that work stays until then or until log-out, the login page and welcome page to match; logging out as a guest asks first ("Log out and delete this workspace?").
• Folder share improvements.
• Transfers e2e: the upload-phase check accepts either busy label (CI race).

🤖 Generated with Claude Code