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__/AddLaneModal.test.tsx

@@ -786,9 +786,25 @@ describe("AddLaneModal — Clone", () => {
       )
     );
     expect(vi.mocked(api.lanes.clone).mock.calls[0]?.[0].credentials).toBeUndefined();
+    expect(vi.mocked(api.lanes.clone).mock.calls[0]?.[0].partial).toBeUndefined();
     await waitFor(() => expect(onAdded).toHaveBeenCalled());
   });
 
+  it("sends partial only when the box is ticked", async () => {
+    vi.mocked(api.lanes.clone).mockResolvedValue({
+      lane: laneFixture({ id: 7 }),
+      created: true,
+      path: "/home/an/code/big",
+    });
+    const user = userEvent.setup();
+    await fillClone(user, "https://git.example.com/o/big.git");
+    await user.click(screen.getByTestId("add-lane-clone-partial"));
+    await user.click(screen.getByRole("button", { name: "Add workspace" }));
+    await waitFor(() =>
+      expect(api.lanes.clone).toHaveBeenCalledWith(expect.objectContaining({ partial: true }))
+    );
+  });
+
   it("asks for a login on ECREDENTIALS and sends it on the retry", async () => {
     vi.mocked(api.lanes.clone)
       .mockRejectedValueOnce(