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/git-identity.js

@@ -386,6 +386,15 @@ async function getAuthor(account) {
   return { name: await get("user.name"), email: await get("user.email") };
 }
 
+/** The domain of a suggested email when the account has no author yet. */
+const DEFAULT_EMAIL_DOMAIN = process.env.AGENTHUB_EMAIL_DOMAIN || "smartgift.vn";
+
+/** `<username>@<DEFAULT_EMAIL_DOMAIN>`, or null without a usable name. */
+function defaultEmail(username) {
+  const local = String(username || "").replace(/[^\w.+-]/g, "");
+  return local ? `${local}@${DEFAULT_EMAIL_DOMAIN}` : null;
+}
+
 /**
  * Set the account's commit author. Neither is a secret, so they may cross
  * sudo's argv; each is one line, a name up to 100 and an email up to 254
@@ -798,6 +807,7 @@ module.exports = {
   defaultName,
   cloneRepo,
   getAuthor,
+  defaultEmail,
   setAuthor,
   sshConfigFor,
   memberHttpsConfig,