Ask for person GitHub usernames

[lgoettgens]

Part of resolving gap-system/gap#4784. This should be merged if and only if gap-system/gap#6497 is merged.

Summary

• reject GitHub usernames entered as profile URLs or @ mentions
• ask for GitHubUsername in wizard person records
• include the new person field in the generated package fixture

Created using Codex (GPT-5.5) codex@openai.com

[codecov]

Codecov Report

❌ Patch coverage is 32.50000% with 27 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.29%. Comparing base (ae42399) to head (ef3c479).

Files with missing lines	Patch %	Lines
gap/input.g	30.76%	27 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #78      +/-   ##
==========================================
- Coverage   68.02%   67.29%   -0.73%     
==========================================
  Files           9        9              
  Lines         985     1006      +21     
==========================================
+ Hits          670      677       +7     
- Misses        315      329      +14     

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[fingolfin]

This looks as if it makes the GitHub user name mandatory? I definitely don't want -- e.g. someone may not even have a GitHub user account. Or they simply don't want to get notifications when a package update is found by the package distro.

[lgoettgens]

It does look so at a first glance, but that's not the case. The actual wizard code only calls the verification function in cases where the user supplied anything else than an empty string. If the user gave an empty string, then instead the field is just put in a comment line of the resulting PackageInfo.g file. This functionality already exists for PostalAddress, website,...

[fingolfin]

OK great then!