Infrastructure: Submission format and input standardization

## Description
Define and implement the standard submission format for model output.

## Requirements
- CMIP-standard variable names (see Table A2 in protocol)
- Specify required grid resolution for submissions
- Handle both coupled and atmosphere-only submissions
- Metadata collection: ECS, TCR, model type, training data description
- Validation script to check submissions are complete and correctly formatted

## Notes
- Must accommodate diverse model architectures (ESMs, neural GCMs, emulators, hybrids)
- input4MIPs forcing data access and format