chore: v2.8.12 — clone queue and progress, session defaults, chat agents, drops as @ mentions

Whole tree from parallel sessions, plus the version bump:
- Clone: a queue with live progress (Add workspace and extra folders),
  clones run under nice/ionice so the machine stays responsive.
- Settings → AI tools → Session defaults: a new session's default
  permission mode / bypass per account.
- Chat lists the background subagents that have not reported back yet.
- A file pasted or dropped into a claude pane goes in as an @ mention.
- Changes panel: say why amend/undo is refused on a pushed commit.
- openapi.yaml regenerated (Artifacts, Host, resumeById).

server/routes/me.js

@@ -57,6 +57,9 @@ const PREF_KEYS = [
   "agent-monitor-notifications",
   "agenthub.defaultTool",
   "agenthub.permissionMode",
+  "agenthub.codex.sandbox",
+  "agenthub.codex.approval",
+  "agenthub.codex.bypass",
   "agenthub.tour",
   "agenthub.chatUi",
   "agenthub.workspace.allTabs",