fix: Include a default border if winborder is not set. (#250)

Without setting a default border, the Yes / No / Cancel buttons and the header are not visible in the confirmation window for tool calls.

Author: slg95

lua/mcphub/utils/ui.lua

@@ -356,6 +356,7 @@ function M.confirm(message, opts)
 
         -- Enhanced window options with better styling
         win_opts.style = "minimal"
+        win_opts.border = vim.o.winborder ~= "" and vim.o.winborder or { "╭", "─", "╮", "│", "╯", "─", "╰", "│" }
         win_opts.title_pos = "center"
         win_opts.title = {
             { " MCPHUB Confirmation ", Text.highlights.header_btn },