[1.10] Add GOVERNANCE.md template

[vbonk]

What needs to be done

Lightweight governance template covering project leadership, decision-making, roles (Maintainer/Contributor/Committer), AI agent governance (agents work via PRs, never push to main, AI config changes require owner review), communication channels, conflict resolution.

Implementation

• Solo maintainer (benevolent dictator) as default model
• Team model as commented alternative
• AI agent governance section is unique differentiator
• init-template asks 'Solo or team?'

Acceptance Criteria

• GOVERNANCE.md exists with template content
• AI agent governance section present
• init-template offers governance model selection

[vbonk]

Completed in Phase 1 PR #87.