Establish organization-wide community defaults #1

Context and request

MSX repositories without repository-local community health files need clear organization-wide fallbacks. The public MSXOrg/.github repository provides that convenience while repository-local files remain the enforceable source required by the Organization Standard.

Acceptance criteria

• The repository remains public and its README explains GitHub's special .github behavior, local-file precedence, and the public visibility requirement.
• .github/CODE_OF_CONDUCT.md, .github/CONTRIBUTING.md, .github/SECURITY.md, and .github/SUPPORT.md are complete organization-wide defaults recognized by GitHub.
• Conduct reports and private support matters use support@msx.no; vulnerabilities, exposed sensitive information or secrets, and weak security controls use the affected repository's private vulnerability reporting or security@msx.no.
• Contribution guidance links to the canonical MSX issue, contribution, review, and pull-request standards and the MSX agent plugin marketplace instead of duplicating them.
• The repository itself carries the applicable MSX baseline: AGENTS.md and client routes, .gitattributes, .gitignore, .github/CODEOWNERS, .github/dependabot.yml, and .github/pull_request_template.md.
• AGENTS.md identifies MSXOrg/docs and private MSXOrg/memory, their entry files and published documentation, and the preferred ~/.msxorg/ clone locations.
• Repository settings enable auto-merge, automatic branch deletion, private vulnerability reporting, Dependabot security updates, non-provider secret patterns, and secret validity checks.
• Markdown and YAML files contain no template placeholders and pass the available targeted validation.

Constraints and non-goals

• Organization fallbacks do not replace repository-local required files.
• This change does not add an organization profile, issue forms, discussion templates, funding configuration, or workflow starter templates.
• The PSModule repository is inspiration only; PSModule-specific text and unresolved placeholders are not copied.

Technical decisions

• Store default community health files under .github/, matching GitHub's documented fallback lookup and the existing PSModule/.github structure.
• Use American English and concise links to the published MSX documentation.
• Use the complete Contributor Covenant 3.0 text with its CC BY-SA 4.0 attribution and only the required reporting-contact customization.
• Do not add a repository-level license. The Contributor Covenant retains its own CC BY-SA 4.0 attribution.
• Agent routes identify repository sources and preferred organization-named clone locations without prescribing an access tool.
• Keep the pull request focused on one reviewable repository bootstrap.

Implementation plan

• Define and run checks for the required file inventory, unresolved placeholders, Markdown, and YAML before adding content.
• Add the repository context, agent-routing, ownership, dependency, and pull-request baseline in one logical commit; push it and open a draft pull request.
• Add the four organization-wide community health defaults in a second logical commit.
• Run the targeted checks and verify GitHub exposes the expected repository metadata and community files.