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).

client/src/components/run/LaneConsolePane.tsx

@@ -218,6 +218,7 @@ export function LaneConsolePane({
             wsBaseUrl={window.location.origin.replace(/^http/, "ws")}
             autoFocus={autoFocus && !(chatable && chat)}
             covered={!!(chatable && chat)}
+            tool={handle.tool}
             // The pane died (double Ctrl+C out of `claude`, `exit`, a crash) —
             // the tab bar moves on (another tab, or the home's prompt box)
             // rather than leaving a dead terminal the user has to click out of.