Disable allow-rename on tool windows (match new_window)

nvim/lazygit emit OSC title sequences; without allow-rename off a tool
could overwrite the window name and scramble the styled @hqt_label.
Mirrors the window-option setup in new_window. Surfaced by final
integration review.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_tmux.py

@@ -1021,7 +1021,7 @@ async def test_new_aux_window_spawns_styles_and_selects(runner):
     runner._exec.side_effect = [
         (0, "0\n", ""),   # _next_window_index: indices [0] -> next index 1
         (0, "@7\n", ""),  # new-window -P -F '#{window_id}'
-        (0, "", ""),      # set-option (automatic-rename + @hqt_label + theme)
+        (0, "", ""),      # set-option (automatic-rename + allow-rename + @hqt_label + theme)
         (0, "", ""),      # select-window
     ]
     wid = await runner.new_aux_window("lazygit", "/proj", ["lazygit"], "lazygit · proj")
@@ -1037,6 +1037,8 @@ async def test_new_aux_window_spawns_styles_and_selects(runner):
     assert calls[2].args[:6] == (
         "set-option", "-w", "-t", "@7", "automatic-rename", "off",
     )
+    # allow-rename off too, so nvim/lazygit OSC titles can't scramble the label.
+    assert "allow-rename" in calls[2].args
     assert "@hqt_label" in calls[2].args
     assert "lazygit · proj" in calls[2].args
     assert "remain-on-exit" not in calls[2].args