Make `M.chat:focus()` optional

Hallo,

      {
        "<leader>ae",
        function()
          local copilot = require("CopilotChat")
          copilot.ask("Explain code underneath")
        end,
        desc = "Explain code underneath (CopilotChat)",
        mode = { "n", "v" },
      },

Consider this snippet as example, everything works fine, my last wish is that I don't want to focus copilot-chat window and for cursor to stay where it was before.

I think relevant line is here, but I don't fully understand logic behind checks if we are indeed in copilot-chat window and if I create flag and optionally disable vim.api.nvim_set_current_win(self.winnr) visual selection stops working.

Start in lua/CopilotChat/ui/chat.lua around line 460 and trace the window-selection logic used by copilot.ask. Check how the proposed optional focus behavior interacts with visual selections, then verify that the cursor remains in its original window when focus is disabled while existing focus behavior still works.