[App] Pre-fill project name from the first selected source folder

What variant of Codex are you using?

Codex App (macOS)

What feature would you like to see?

Summary

When creating a project, if the Project name field is empty and the user selects a source folder, pre-fill the project name with that folder's basename.

For example:

• Selected source folder: /path/to/landing-page
• Suggested project name: landing-page

Motivation

For most projects, the project name will be the same as the primary source directory. Pre-filling it would remove a redundant typing step and make project creation feel more natural.

Suggested behavior

• Only pre-fill the name when the field is empty.
• Use the basename of the first selected source folder.
• Keep the suggested name fully editable.
• Never overwrite a name the user has entered or edited.

Screenshot

Additional information

The screenshot shows the current state after selecting the landing-page source folder: the project-name field remains empty.

Related: #21996 discusses broader project naming and filesystem-path consistency, but does not cover automatically suggesting a project name from a selected existing folder.

Start by locating the Codex App project-creation flow and the source-folder selection handling. Verify how the project-name field tracks empty versus user-edited values, then confirm that selecting the first source folder fills only an empty field with its basename and leaves entered names unchanged.