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/__tests__/PaneChat.test.tsx

@@ -430,7 +430,7 @@ describe("PaneChat — the unsent prompt", () => {
     expect(screen.getByPlaceholderText("Write a message…")).toHaveValue("half typed");
     expect(screen.getByText("a.ts")).toBeInTheDocument();
     fireEvent.click(screen.getByTestId("pane-chat-send"));
-    expect(submitToRun).toHaveBeenCalledWith("agenthub-lane-1", "half typed @src/a.ts", []);
+    expect(submitToRun).toHaveBeenCalledWith("agenthub-lane-1", "half typed @src/a.ts ", []);
     await waitFor(() => expect(localStorage.getItem("agenthub.chat.draft.s1")).toBeNull());
   });
 
@@ -462,7 +462,9 @@ describe("PaneChat — the unsent prompt", () => {
     fireEvent.click(screen.getByTestId("pane-chat-send"));
     expect(submitToRun).toHaveBeenCalledWith(
       "agenthub-lane-1",
-      'read @"/home/u/My Docs/spec.md" @/home/u/b.ts',
+      // A trailing space: an @ mention at the end would leave claude's file
+      // suggester open, and it takes the Enter.
+      'read @"/home/u/My Docs/spec.md" @/home/u/b.ts ',
       []
     );
   });