Initialize repository governance, handbook, and docs CI workflows

[csecrestjr]

Motivation

• Provide a minimal, reviewable open-source foundation for the NTARI Developer Portal including contributor-facing governance and handbook guidance.
• Establish consistent editor and repository formatting with .editorconfig and .gitignore to reduce noise from local tooling.
• Add intake and collaboration templates to standardize issue and pull request workflows with GitHub Issue Forms and a PR template.
• Introduce quality gates for documentation with automated checks to catch broken links, style problems, and spelling errors early.

Description

• Added community and governance files including CONTRIBUTING.md, CODE_OF_CONDUCT.md, SECURITY.md, CODEOWNERS, and an updated README.md.
• Created structured issue forms under .github/ISSUE_TEMPLATE/ for bug reports, feature requests, documentation improvements, and RFCs, and added .github/PULL_REQUEST_TEMPLATE.md.
• Implemented three GitHub Actions workflows: markdown-lint.yml (markdownlint), broken-link-check.yml (lychee), and spellcheck.yml (codespell), and configured least-privilege permissions for workflows.
• Added a comprehensive docs/engineering-handbook/ with chapter pages for purpose, principles, roles, workflow, repo standards, and many placeholder pages, plus REPOSITORY_READINESS_REPORT.md, .editorconfig, and .gitignore.

Testing

• No automated CI runs were executed as part of this change; the new workflows are configured to run on future push and pull_request events and scheduled runs.
• Workflow YAML files and templates were added to enable automated markdownlint, lychee link checks, and codespell spellchecks in subsequent PRs.
• Manual review of added Markdown files was performed to ensure basic readability and internal linking conventions, with placeholders used where full content will be added later.

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Codex Task