feat: v2.7.8 — Artifacts hub, clone related repos as extra folders, quieter resume prompt

- Artifacts (/artifacts): claude.ai pages sessions publish (captured from the
  Artifact tool's hook), pinned workspace files, skills and plugins, each
  kept as a snapshot; shared ones appear in a Hub and a skill or plugin
  installs into the viewer's own account (server/lib/artifacts.js,
  /api/artifacts, docs/plans/artifacts/).
- Workspace extra folders: clone one or more related repos beside the
  workspace and add them in one step (POST /api/lanes/:id/sources/clone).
- A pane that ended by itself while tmux kept running is no longer offered
  for resume (tmux.serverStartedAt in reconcileOrphans).
- Changes panel: a folder that is not a git repo opens on Files, and its
  files open from there.
- Plus the parallel sessions' work in this tree: File Explorer button in the
  panel header, user delete, RSA SSH keys, chat/terminal and pet fixes.

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

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

@@ -57,7 +57,8 @@
     "enabled": "{{name}} enabled",
     "password": "{{name}}'s password reset",
     "workspace": "Workspace given to {{name}}",
-    "updated": "{{name}} updated"
+    "updated": "{{name}} updated",
+    "deleted": "{{name}} was deleted."
   },
   "errors": {
     "EREAUTH": "Your password is wrong.",
@@ -72,7 +73,8 @@
     "ENOTOWNED": "That workspace is not this user's any more.",
     "EOWNERFOLDER": "That workspace's folder belongs to another user's account.",
     "EBADROLE": "Unknown role.",
-    "ELOCALMODE": "Accounts are managed in server mode only."
+    "ELOCALMODE": "Accounts are managed in server mode only.",
+    "ELASTADMIN": "The last admin cannot be deleted."
   },
   "readOnly": "Analysts can view accounts but not change them.",
   "auditTitle": "Audit log",
@@ -187,5 +189,12 @@
       "codex": "An OpenAI API key (sk-…), or the whole ~/.codex/auth.json after `codex login` with a ChatGPT account."
     },
     "refreshFailed": "refresh failed"
+  },
+  "delete": {
+    "button": "Delete user",
+    "title": "Delete {{name}}?",
+    "body": "This deletes {{name}} for good: their login, {{count}} workspace(s), and their Linux account with the whole home folder (/srv/agenthub/users/{{user}}) — every file and all source code in it. It cannot be undone. Session history and the audit log stay.",
+    "confirm": "Delete for good",
+    "needsPassword": "Enter your own password below first."
   }
 }