Add the Maintainers Wanted GitHub template (github-maintainers-wanted) #297

Part of #5. For open source projects looking for new maintainers.

Idea
A small "Maintainers wanted" label in the accent color at the top, the repository name large under it ("acme/csv-stream") with a one-line pitch ("A streaming CSV parser for Node"). Then the star and open issue counts side by side ("4.2k stars", "38 open issues"), up to three short lines on what you'd help with ("Review pull requests", "Triage new issues", "Cut releases"), and the site name at the bottom.

Template details

• File: src/templates/github/maintainers-wanted.ts, id github-maintainers-wanted
• Fields: commonFields.title (the repository), commonFields.description (the pitch, optional), stars (text, optional, default "4.2k stars"), openIssues (text, optional, default "38 open issues"), help1 to help3 (text, optional, defaults "Review pull requests", "Triage new issues" and "Cut releases"), commonFields.siteName, commonFields.bgColor, commonFields.accentColor, commonFields.textColor

Where to look

• Closest reference: src/templates/github/repo-card.ts (a repository with its stats), src/templates/blog/table-of-contents.ts (a short list where blank rows are skipped)

Acceptance criteria

• A long repository name and pitch shrink with autoFontSize() and then truncate, blank help lines are skipped with no gaps, and an empty pitch, stars, openIssues or site name (or only spaces) hides cleanly
• The label and any accent text stay readable on a light background
• Re-exported in src/templates/github/index.ts and registered in the GitHub block of src/templates/registry.ts
• Meets the shared template checklist in Add new card-style OG image templates #5

One template per contributor at a time, so more people get a chance.

Want to work on this? Comment below and I'll assign it to you. Please take one issue at a time, branch off dev, and open your PR against dev with Closes #297 in the description.