Validate RIMS core design against Cellar Sync use cases

[fusion94]

Description

RIMS should not be validated only against armory-core. A reusable framework needs a second real domain to confirm which abstractions are structural and which are domain artifacts.

This issue uses cellar-sync as a validation case for the RIMS direction.

Acceptance Criteria

• Identify core cellar-sync use cases relevant to RIMS
• Test whether the proposed RIMS model supports those use cases cleanly
• Identify any gaps or awkward abstractions exposed by cellar-sync requirements
• Document what cellar-sync needs from RIMS core
• Document what cellar-sync should keep in a domain module
• Update RIMS design notes based on the findings