chore: v2.8.5 — Trash opens on one folder per user, server setup installs S3

- Files → Trash: ONE sidebar entry. An admin's opens on a folder per user's
  Trash (My Trash first, item counts from GET /api/homes/trash, an unreadable
  one showing its error); a folder opens that user's Trash (path bar
  Trash › user, Up back to the folders). An admin may restore/purge in
  another user's Trash (audited); purging asks first. The merged "All users"
  list is gone from the UI.
- A home's Trash is its user's whole recycle bin (home store + host store,
  items tagged `store`).
- `agenthub server setup` installs one Linux user per account on Linux by
  default (`--no-system` opts out); install-system messages drop `sudo`.
- Settings → Git: the author email suggests <username>@<AGENTHUB_EMAIL_DOMAIN>.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/lib/artifacts.js

@@ -1146,7 +1146,7 @@ async function installSkill(req, row, { replace = false } = {}) {
     );
     if (acct) {
       if (!runAs.writeAsCanMove()) {
-        throw fail("EUPGRADE", "replacing needs the updated helper: run `sudo agenthub server install-system` once");
+        throw fail("EUPGRADE", "replacing needs the updated helper: run `agenthub server install-system` once");
       }
       runAs.mkdirAs(acct, path.dirname(aside));
       await runAs.writeAsAsync(acct, target, ["move", aside]);