feat: auto-wrap variables.json content in Variables object

[rvwatch]

Summary

• Allow customers to use flat variables.json files without Variables wrapper
• CLI automatically wraps raw variables in {Variables: ...} structure
• Update help text to clarify new flat JSON format support

Problem

Customers' variables.json files typically contain flat JSON like:

{
    "hello": "world"
}

But the API requires variables to be wrapped in a Variables object:

{
    "Variables": {
        "hello": "world"
    }
}

This forced customers to manually restructure their files.

Solution

The CLI now automatically wraps flat variables.json content in the required Variables structure, allowing customers to use their existing files directly.

Changes

• Modified src/commands/orchestrator/rules/eval.ts lines 148-151 to auto-wrap variables
• Updated help documentation in messages/orchestrator.rules.eval.md
• Maintains backward compatibility with existing variable files

Test Plan

• All existing unit tests pass
• All integration (NUT) tests pass
• Linting passes
• Manual testing with flat variables.json files works
• Backward compatibility confirmed