[groupsky]

Refs #97

Adds the files of GitHub's community standards. They point to AGENTS.md, SECURITY.md and docs/releasing.md and do not copy them.

Progress

• CONTRIBUTING.md
• CODE_OF_CONDUCT.md: Contributor Covenant 2.1 text is in. Waits for Geno: the contact for a report ([INSERT CONTACT METHOD] is still in the file; question on docs: complete GitHub's community standards (contributing, code of conduct, templates) #97).
• .github/ISSUE_TEMPLATE/: bug report, feature request, config.yml
• .github/pull_request_template.md
• AGENTS.md lists the new files
• Community profile shows every file as done (after merge). Geno decides on "Accept content reports" (question on docs: complete GitHub's community standards (contributing, code of conduct, templates) #97).

Choices

• Blank issues stay on. Most issues here are written by the owner and by agents, as free markdown with a "Done when" list. A form for each of them would only get in the way. The forms are for people who come new.
• Issue forms (YAML), not markdown templates. A form can make the version and the OS required, and it shows the warning about private data at the top.
• config.yml links to security/advisories/new, the private report of SECURITY.md.
• Reviews: a docs review and the security-reviewer agent on the whole diff; their findings (dependency list copied wrong, ssh-agent journal missing, "every issue has Done when") are fixed. A second security review of the fix found nothing.
• SUPPORT.md and GOVERNANCE.md are not needed now. nodkey has one maintainer. Support is an issue; the rules are in AGENTS.md and CONTRIBUTING.md. They can come when there are more maintainers.