Add v3LR to baseline in Taylor Diagram and CMIP comparison plots

[chengzhuzhang]

Description

What Now Works:

1. Taylor Diagrams: E3SMv3 baselines appear automatically via existing CSV files
   - Uses taylor_diag_E3SMv3.csv files (the metrics are generated for amip_0101, and historical_0101 e3sm diags run from @wlin7 )
   - Code automatically discovers via glob pattern E3SMv*.csv
2. CMIP6 Box-and-Whisker Plots: E3SM-3-0 now appears as:
   - Part of ensemble statistics (included in box-and-whisker calculations)
   - Individual green triangle point (distinct from E3SMv1 blue > and E3SMv2 red <)
   - Positioned at x + 1.4 (offset from other models)
3. Data Integration:
   - E3SM-3-0 historical data added to cmip6_historical_seasonal_rmse_202203.csv
   - E3SM-3-0 AMIP data added to cmip6_amip_seasonal_rmse_202206.csv

• Closes [Feature]: Extend baseline datasets to include v3.LR in Taylor Diagram and CMIP comparison plots #998

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

If applicable:

• New and existing unit tests pass with my changes (locally and CI/CD build)
• I have added tests that prove my fix is effective or that my feature works
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have noted that this is a breaking change for a major release (fix or feature that would cause existing functionality to not work as expected)

[chengzhuzhang]

@wlin7 since you reminded me about this update. Could you quickly review the results here? let me know if you'd like any changes. And FYI I re-used the metrics from your historical and amip 0101 e3sm_diags runs.

[chengzhuzhang]

@wlin7 could you please review? Thanks!

[chengzhuzhang]

@wlin7 hey wuyin, could you have a quick review of this PR? I'm hoping to have this merged, for a weekly test.