MOM6 data assimilation script for CESM3

## MOM6 Data Assimilation Script for CESM3

**Summary:**
Develop a data assimilation (DA) script for MOM6 within CESM3 to enable integration with DART.

**Motivation:**
Enabling DA in in CESM with MOM6 in a more user friendly, modular, maintainable format than the existing CAM/CLM scripts which are 1000s of lines of csh (e.g. https://github.com/NCAR/DART/blob/main/models/cam-fv/shell_scripts/cesm2_0/setup_advanced)

**Goals:**
- Create a robust `assimilate.sh` or `assimilate.py` script for MOM6 in CESM3.
- Ensure compatibility with DART and CESM3 workflows.
- Handle regional MOM6 configurations, if there are differences between global and regional cases.
- Document the script and user options.

**Approach:**
- Review existing DA scripts for MOM6 and integrate with CESM3’s CIME system.
- Decide whether to use Python or bash
- Use the existing bank of WOD observations available on Glade.
- Test with MOM6 configurations, regional and global
- Document usage, setup, and troubleshooting.

**Skills Needed or To Be Gained:**
- Bash scripting
- Python
- CESM3 / CIME case management

**Possible Challenges:**
- Inflation files on the initial DA run vs. subsequent DA runs.
- Different observation requirements other than existing 12 hour observation sequences on Glade.

**References:**
- [CROCODILE DART Assimilate Script](https://github.com/CROCODILE-CESM/DART/blob/main-oct25/models/MOM6/cesm_scripts/assimilate.sh)
- [CIME Case Run Documentation](https://github.com/ESMCI/cime)