fix: Fix number key selection in PackMenu

The menu's number key selection wasn't working due to incorrect loop termination logic.
Fixed by using explicit break statements when a valid selection is made or when
exit keys (q/Esc) are pressed.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: mplusp

lua/pack-manager/ui.lua

@@ -338,11 +338,13 @@ function M.menu()
       local selected = key - string.byte('0')
       if selected <= #menu_options then
         result = menu_options[selected].action
+        break
       end
     elseif key == 27 or key == string.byte('q') then -- Escape or q
       result = nil
+      break
     end
-  until result ~= nil or result == nil and (key == 27 or key == string.byte('q'))
+  until false
 
   close_window(win)
   return result