fix: detect buffer mismatch on toggle (e.g. :e opened file over terminal)

When terminal occupies main window and user directly opens a file
(:e somefile) in that window, the window's buffer no longer matches
term.bufnr. Previously this caused the hide path to incorrectly swap
back original_bufnr, wiping the user's file. Now we detect mismatch,
clear winid/borrowed, and re-evaluate use_main — which will correctly
fall through to a split when a real file is present.

lua/QQdock/init.lua

@@ -110,6 +110,11 @@ function M.open(cmd)
 
   -- 已打开 → 关闭/隐藏，终端进程继续
   if term and term.winid and vim.api.nvim_win_is_valid(term.winid) then
+    -- 窗口 buffer 已被替换（用户直接 :e 打开了文件）→ 当作已隐藏
+    if vim.api.nvim_win_get_buf(term.winid) ~= term.bufnr then
+      term.winid = nil
+      term.borrowed = nil
+    else
       if config.debug then
         vim.notify('QQdock: hide [' .. name .. ']', vim.log.levels.INFO)
       end
@@ -123,6 +128,7 @@ function M.open(cmd)
       term.borrowed = nil
       return
     end
+  end
 
   -- 需要打开 → 基于当前窗口计算布局
   local direction, size = get_layout()