feat: right-click menus in Files/Users/Artifacts; several SSH keys and accounts per host

- Files: right-click a sidebar workspace (Open, Copy path) or home (Open,
  Open Trash), a path crumb (Open, Download as zip, Paste into, Copy path),
  a Trash row (Restore, Copy path, Delete forever), the Trash area (Refresh,
  Empty Trash) and an admin's per-user Trash folder (Open, Empty Trash).
- Users: row menu (Edit + Open home in Files for an admin, Copy username/email).
- Artifacts: card menu repeating its buttons, plus Copy link for a page.
- Git identity: named SSH keys beside the default ones (id_<type>_<name>,
  max 10, DELETE ?id=); SSH logins per alias (`ssh://<alias>/` →
  `ssh://<user>@<host>/`, so several AWS CodeCommit accounts share a host),
  each optionally tied to one key (`agenthub.<from>.sshKey`) — a clone of
  that URL offers only that key and persists it. Terminal sshCommand follows
  the keys. Settings → Git: "More SSH keys" + account name/key in the AWS and
  other-host forms. Docs/API.md, OpenAPI updated.

docs/API.md

@@ -1067,12 +1067,12 @@ cannot collide on `index.lock`.
 #### Your git identity
 
 ```
-GET    /api/me/git                 { account: "member"|"host", writable, ssh: { type, publicKey, fingerprint, terminal: "on"|"off"|"foreign" } | null (the first key), sshKeys: [{ type, publicKey, fingerprint }] (ed25519 first), sshTerminal, https: [{ protocol, host, username, hasToken }], author: { name, email }, defaultEmail }
-POST   /api/me/git/ssh-key         Make the SSH key of `type` — Body: { replace?, type?: "ed25519" | "rsa" } (409 EEXISTS when that TYPE exists, without replace; the other type is kept — an account may hold one of each, and every ssh git offers both) → 201, same shape
-DELETE /api/me/git/ssh-key         Delete the key of `?type=ed25519|rsa`, or every key without it (404 ENOTFOUND, 400 EBADKEYTYPE) — also removes our terminal `core.sshCommand`
-PUT    /api/me/git/ssh-terminal    Use the key for git typed in the account's own terminal — Body: { on } — sets/unsets `core.sshCommand` in its `~/.gitconfig` (ours first, then `~/.ssh/id_*`); on by default when a member makes a key; 409 EFOREIGNSSH over one the user wrote, which is never touched
-PUT    /api/me/git/ssh-user        The SSH login name for one host — Body: { host, user } — writes `url."ssh://<user>@<host>/".insteadOf "ssh://<host>/"` to the account's `~/.gitconfig` (replacing ours for that host), so a plain `ssh://<host>/…` URL logs in as `user` (AWS CodeCommit: the IAM SSH key ID `APKA…`); 400 EBADHOST / EBADSSHUSER. Listed as `sshUsers: [{host, user}]` in GET /api/me/git
-DELETE /api/me/git/ssh-user/:host  Drop that rule (404 ENOTFOUND); any other `insteadOf` the user wrote is never touched
+GET    /api/me/git                 { account: "member"|"host", writable, ssh: { type, publicKey, fingerprint, terminal: "on"|"off"|"foreign" } | null (the first key), sshKeys: [{ id, type, name, publicKey, fingerprint }] (default ed25519, default rsa, then named keys by name; `name` null for a default key, `id` = its file name), sshTerminal, sshUsers: [{ host, user, alias, key }], https: [{ protocol, host, username, hasToken }], author: { name, email }, defaultEmail }
+POST   /api/me/git/ssh-key         Make an SSH key — Body: { replace?, type?: "ed25519" | "rsa", name? } — without `name` the DEFAULT key of that type (`id_ed25519`/`id_rsa`), with `name` (lowercase letters, digits, `-`, ≤ 32; 400 EBADKEYNAME) one more beside it, `id_<type>_<name>` — for another AWS account or a second GitHub user. 409 EEXISTS when that key exists without replace, or the name is taken by a key of the other type; 409 ETOOMANYKEYS past 10 keys → 201, same shape
+DELETE /api/me/git/ssh-key         Delete one key — `?id=<key id>` (400 EBADKEYNAME for a malformed id), or the default key of `?type=ed25519|rsa` — or every key without either (404 ENOTFOUND, 400 EBADKEYTYPE). A login naming a deleted key goes back to every key; our terminal `core.sshCommand` follows the keys and goes with the last one
+PUT    /api/me/git/ssh-terminal    Use the keys for git typed in the account's own terminal — Body: { on } — sets/unsets `core.sshCommand` in its `~/.gitconfig` (every AgentHub key first, then `~/.ssh/id_*`; rewritten as keys are made or deleted while on); on by default when a member makes a key; 409 EFOREIGNSSH over one the user wrote, which is never touched
+PUT    /api/me/git/ssh-user        An SSH login — Body: { host, user, alias?, key? } — writes `url."ssh://<user>@<host>/".insteadOf "ssh://<from>/"` to the account's `~/.gitconfig`, `<from>` = `alias` or the host itself (replacing ours for that host/alias), so `ssh://<from>/…` logs in as `user` (AWS CodeCommit: the IAM SSH key ID `APKA…`). `alias` (lowercase letters, digits, `-`, NO dot — 400 EBADALIAS) is one more account on the same host: two AWS accounts clone as `ssh://aws-prod/v1/repos/x` and `ssh://aws-dev/v1/repos/x`. `key` (a key id, 400 ENOKEY) is stored as `agenthub.<from>.sshKey` there: a clone of a `ssh://<from>/…` URL then offers ONLY that key (`IdentitiesOnly`) and persists it into the clone's config; without it every key is offered. 400 EBADHOST / EBADSSHUSER
+DELETE /api/me/git/ssh-user/:from  Drop the rule of that host or alias and its key link (404 ENOTFOUND); any other `insteadOf` the user wrote is never touched
 POST   /api/me/git/https           Save an https login — Body: { host, username, password }
 DELETE /api/me/git/https/:host     Delete one (404 ENOTFOUND)
 PUT    /api/me/git/author          Commit author — Body: { name, email } (400 EBADAUTHOR) — `git config --global user.name/email` as the account. A new SSH key is labelled with that email, else `defaultEmail` (`<username>@smartgift.vn`; `AGENTHUB_EMAIL_DOMAIN` overrides the domain), also returned by GET /api/me/git as the email form's suggestion