Added ESGF links for v3LR data (#69)

* Add ESGF links for E3SM v3 data

Update the get_esgf() function to generate ESGF links for v3 data using the new CMIP6-E3SM-Ext project on aims2.llnl.gov. Update the v3 simulation CSV to enable CMIP link generation.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

* add links for v3 CMIP

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Co-authored-by: Claude <[email protected]>

Author: chengzhuzhang