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/lanes/__tests__/WorkspaceHome.test.tsx

@@ -245,7 +245,9 @@ describe("WorkspaceHome", () => {
     // As the Workspace page: `&run=` replaces the home with the session view.
     function HomeUntilRun() {
       const [params] = useSearchParams();
-      return params.get("run") ? null : <WorkspaceHome lane={lane()} onMenuAction={() => undefined} />;
+      return params.get("run") ? null : (
+        <WorkspaceHome lane={lane()} onMenuAction={() => undefined} />
+      );
     }
     const user = userEvent.setup();
     render(