Merge add-create-project-interactive into add-create-repo-interactive

Brings in main's .git-suffix refusal for repo create, resolved onto this branch's RunE and extended to the wizard:

• refuseGitSuffixRepoName applies to the trimmed name before the direct/refusal/wizard branch, so neither path reaches a request.
• The wizard's validateName refuses the same names on the page, suggesting the trimmed spelling.

Also from the trail #1454 re-review:

• Without a terminal, a missing input gets the no-terminal refusal even when create flags were given; the flag-form one suggests being prompted, which nothing can do there.
• The 409 note no longer insists on another name.
• Help and cli-conventions wording.