Part of #31653
"use_system_path_prompts": false is needed in settings for these to appear as modals for new file save and file open.

Fixed a very subpar experience of the "save new file" Zed modal, compared to a similar "open file path" Zed modal by uniting their code.

Before:

After:

Also

• alters both prompts to start in the current worktree directory, with the fallback to home directory.
• adjusts the code to handle Windows paths better

Release Notes:

• Improved Zed prompts for file path selection