docs(governance): add SIG overlay, MAINTAINERS.md, and continuity rules

[WilliamBerryiii]

Description

Introduces a foundation-style governance overlay for hve-core: a SIG (Special Interest Group) structure with six initial charters, a MAINTAINERS.md roster with named SIG chairs and Pro Tem terms, and continuity/quorum rules in GOVERNANCE.md. Documentation-only — no code, no AI artifacts, no dependency changes.

A companion RFC proposal document explaining rationale and trade-offs has been prepared for maintainer review (kept out of the commit; available on request).

Related Issue(s)

None — internal governance proposal pending maintainer review.

Type of Change

Code & Documentation:

• Documentation update

Testing

Validation chain executed locally against the staged changes:

• npm run format:tables — clean (no changes applied)
• npm run lint:md — 204 files, 0 errors
• npm run lint:frontmatter — pass
• npm run spell-check — pass (new contributor handles added to .cspell.json)

Checklist

Required Checks

• Documentation is updated (if applicable)
• Files follow existing naming conventions
• Changes are backwards compatible (if applicable)
• Tests added for new functionality (if applicable) — N/A, documentation-only

Required Automated Checks

• Markdown linting: npm run lint:md
• Spell checking: npm run spell-check
• Frontmatter validation: npm run lint:frontmatter
• Skill structure validation: npm run validate:skills — N/A, no skill changes
• Link validation: npm run lint:md-links — not run locally; CI will execute
• PowerShell analysis: npm run lint:ps — N/A, no PowerShell changes
• Plugin freshness: npm run plugin:generate — N/A, no collection changes
• Docusaurus tests: npm run docs:test — not run locally; CI will execute

Security Considerations

• This PR does not contain any sensitive or NDA information
• Any new dependencies have been reviewed for security issues — N/A, no dependencies added
• Security-related scripts follow the principle of least privilege — N/A, no script changes

Additional Notes

Files changed:

• .github/MAINTAINERS.md (new) — five-row roster with GitHub handles, SIG chair assignments, and Pro Tem markers
• GOVERNANCE.md — adds SIG section, Continuity & Quorum rules (3-minimum, Pro Tem 3-month renewable once), Public Activity rule, decision tiers (Routine / Significant / Breaking / Governance), Chair rotation rules
• docs/community/sigs/README.md (new) — SIG index with WG deferral
• docs/community/sigs/sig-engineering/CHARTER.md (new)
• docs/community/sigs/sig-standards/CHARTER.md (new)
• docs/community/sigs/sig-security/CHARTER.md (new)
• docs/community/sigs/sig-rai/CHARTER.md (new)
• docs/community/sigs/sig-data-science/CHARTER.md (new)
• docs/community/sigs/sig-emerging-ai/CHARTER.md (new)
• .github/CODEOWNERS — self-protect governance files; SIG ownership stub commented for activation post-approval
• .cspell.json — proper-noun additions for new contributor handles

Marked as draft for maintainer review and discussion before merge.

🤖 Crafted with precision by ✨Copilot following brilliant human instruction, then carefully refined by our team of discerning human reviewers.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.63%. Comparing base (0d4452b) to head (a506678).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1448      +/-   ##
==========================================
- Coverage   87.64%   87.63%   -0.01%     
==========================================
  Files          65       65              
  Lines       10152    10152              
==========================================
- Hits         8898     8897       -1     
- Misses       1254     1255       +1     

Flag	Coverage Δ
pester	85.02% <ø> (-0.02%)	⬇️

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see 1 file with indirect coverage changes

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