feat(calm-models): add control diff to diff engine

[aamanrebello]

Description

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📚 Documentation update
• 🎨 Code style/formatting changes
• ♻️ Refactoring (no functional changes)
• ⚡ Performance improvements
• ✅ Test additions or updates
• 🔧 Chore (maintenance, dependencies, CI, etc.)

Affected Components

• CLI (cli/)
• Schema (calm/)
• CALM AI (calm-ai/)
• CALM Hub (calm-hub/)
• CALM Hub UI (calm-hub-ui/)
• CALM Server (calm-server/)
• CALM Widgets (calm-widgets/)
• Documentation (docs/)
• Shared (shared/)
• VS Code Extension (calm-plugins/vscode/)
• Dependencies
• CI/CD

Commit Message Format ✅

Testing

• I have tested my changes locally
• I have added/updated unit tests
• All existing tests pass

Checklist

• My commits follow the conventional commit format
• I have updated documentation if necessary
• I have added tests for my changes (if applicable)
• My changes follow the project's coding standards

[gjs-opsflo]

Scope correction: gjs-opsflo isn't a CODEOWNER for calm-models/ (per .github/CODEOWNERS, my coverage is /calm-guard/ + /calm-studio/; this path falls under * @finos/architecture-as-code-maintainers). Review ended up in my queue but the canonical owners for the diff engine are @rocketstack-matt / @aidanm3341 / @lbulanti-ms — calm-hub-ui's timeline is the primary consumer.

Treating this review as withdrawn/advisory. GitHub won't let me delete a submitted review, so a maintainer dismiss is the only way to clear the CHANGES_REQUESTED state.

Apologies for the noise.