Report & optional bot reminder for issues closed without contributor credits

Problem/Motivation

Maintainers (me) sometimes forget to assign contributor credits when setting issues to Fixed. This causes missed recognition and inaccurate contribution records. A simple project-level way to spot these would help maintainers quickly make things right.

Proposed resolution

• Project-level “Missing Credits” report: List issues marked Fixed with zero credits, with basic filters (e.g., date range) and CSV export. Use the read-only Contribution Records API.
• Optional reminder on close: If enabled per project, post a gentle comment when an issue is set to Fixed without credits, prompting the maintainer to review and assign credits. Maybe confirming “Yes, nobody should be credited on this one” or something along those lines.

User interface changes

• New project-level “Missing Credits” report page.
• Project setting to enable/disable the “no-credits” reminder comment.