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.

client/src/i18n/locales/en/artifacts.json

@@ -29,6 +29,7 @@
   "shareDone": "Shared to the Hub",
   "unshareDone": "Removed from the Hub",
   "open": "Open",
+  "copyLink": "Copy link",
   "preview": "Preview",
   "download": "Download",
   "install": "Install",

client/src/i18n/locales/en/lanes.json

@@ -596,6 +596,7 @@
   "fx.trashAt": "Trash ({{name}})",
   "fx.trashFoldersHint": "Each folder is one user's Trash — open it to restore or delete forever.",
   "fx.trashFolderEmpty": "Empty",
+  "fx.openTrash": "Open Trash",
   "fx.purged": "Deleted forever.",
   "fx.emptyTrashTitle": "Empty the Trash?",
   "fx.emptyTrashBody": "All {{count}} items in {{where}} will be deleted forever. This cannot be undone.",

client/src/i18n/locales/en/settings.json

@@ -937,7 +937,21 @@
     "otherHost": "Host",
     "otherUser": "User name",
     "otherSaved": "SSH user saved for {{host}}",
-    "privateNote": "Only the public key is ever shown; the private key never leaves the server."
+    "privateNote": "Only the public key is ever shown; the private key never leaves the server.",
+    "anyKey": "Any key",
+    "defaultEd": "ED25519 (default)",
+    "defaultRsa": "RSA (default)",
+    "loginKey": "Key",
+    "alias": "Account name",
+    "aliasPlaceholder": "name (optional)",
+    "aliasHint": "Leave empty for the default account of this host. Give a name (e.g. aws-prod, lowercase, no dot) for one more account: clone it as ssh://<name>/…",
+    "awsMany": "Several AWS accounts? Make one more RSA key below for each, upload it to that account, then save its SSH key ID here with an account name and that key. Clone each with ssh://<account name>/v1/repos/<repo>.",
+    "moreKeysTitle": "More SSH keys",
+    "moreKeysSub": "One per extra account — another AWS account, a second GitHub user. A login that names its key uses only that key.",
+    "newKey": "New key",
+    "keyName": "Key name",
+    "keyNamePlaceholder": "e.g. aws-prod",
+    "keyType": "Key type"
   },
   "gitCreds": {
     "title": "Git credentials",

client/src/i18n/locales/en/users.json

@@ -234,5 +234,10 @@
     "errors": {
       "ETMUXSTUCK": "The server did not stop. Run the `sudo kill -9` command shown, as root, on the server."
     }
+  },
+  "rowMenu": {
+    "openHome": "Open home in Files",
+    "copyUsername": "Copy username",
+    "copyEmail": "Copy email"
   }
 }