[BUG] focus_after_send has no effect with provider = "none"

[cperalt]

Bug Description

focus_after_send = true silently has no effect when terminal.provider = "none". No
warning or error is shown — the option is accepted but never fires, leaving users with
external terminal setups unable to use this feature.

To Reproduce

1. Configure the plugin with terminal.provider = "none" and focus_after_send = true
2. Open a file in Neovim and make a visual selection
3. Run ClaudeCodeSend
4. Focus remains on Neovim — Claude session is never focused

Expected Behavior

Either:

• focus_after_send accepts a user-defined callback so external terminal users can
  implement their own focus logic, or
• A warning is emitted when focus_after_send = true is set alongside provider = "none"
  to make it clear the option has no effect

Environment

• Neovim version: [e.g. 0.10.0]
• Claude Code CLI version: [e.g. latest]
• OS: macOS
• Plugin version: [e.g. latest]

Error Messages

No error messages — the option silently does nothing.

Additional Context

This affects any user running Claude Code in an external terminal (tmux pane, wezterm
split, etc.) rather than a managed provider. A callback-based API would make this
first-class without requiring the plugin to know about specific terminal emulators:

require("claudecode").setup({
  focus_after_send = function()
    -- user-defined focus logic
  end,
})

-- Workaround: wrap the send keymap in a Lua function that manually triggers a tmux command
after sending:

local function send_and_focus_claude()
  vim.cmd("ClaudeCodeSend")
  local pane = vim.fn.system(
    "tmux list-panes -F '#{pane_index}:#{pane_current_command}' | grep -i claude | cut -d:
-f1 | head -1 | tr -d '\n'"
  )
  if pane ~= "" then
    vim.fn.system("tmux select-pane -t " .. pane)
  end
end

{ "<leader>cs", send_and_focus_claude, mode = "v" }

-- Works but requires every external terminal user to reimplement this themselves.