feat: add esgf_data_catalog fixture and solver regression baselines

[lewisjared]

Description

Add infrastructure for testing solver behavior without requiring sample data downloads:

• esgf_data_catalog fixture: Session-scoped fixture in conftest_plugin.py that provides dict[SourceDatasetType, pd.DataFrame] from pre-generated parquet catalogs. Tests that only need DataFrames for solver logic can use this instead of the data_catalog fixture (which triggers sample data downloads).

• PMP climatology parquet catalog: Generated from the pooch-cached PMP_obs4MIPsClims data (25 entries), enabling PMP solver regression testing.

• Per-provider regression baselines: Deterministic, alphabetically-sorted YAML baselines for example (3175 lines), ESMValTool (5120 lines), ILAMB (440 lines), and PMP (6026 lines). Any change to solver logic, constraints, or data requirements will show up as a diff. Regenerate with --force-regen.

• Fixture swap: test_solve_helpers.py and test_solve_regression.py now use esgf_data_catalog instead of data_catalog, removing their dependency on sample data.

Checklist

Please confirm that this pull request has done the following:

• Tests added
• Documentation added (where applicable)
• Changelog item added to changelog/

[Copilot]

Pull request overview

Adds ESGF parquet-catalog infrastructure and regression baselines so solver behavior can be tested deterministically without downloading sample datasets.

Changes:

• Introduces solve_helpers utilities to generate/load parquet catalogs and produce regression-friendly solver outputs.
• Adds a session-scoped esgf_data_catalog fixture that fails fast when the parquet catalogs are missing.
• Adds solver regression tests and per-provider YAML baselines (generated output) plus a catalog-generation script.

Reviewed changes

Copilot reviewed 7 out of 13 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
scripts/generate_esgf_catalog.py	CLI to scan local archives and write parquet catalogs used by tests.
packages/climate-ref/src/climate_ref/solve_helpers.py	Core helpers to generate/load catalogs and format solver outputs for regression testing.
packages/climate-ref/src/climate_ref/conftest_plugin.py	Adds esgf_data_catalog fixture backed by parquet catalogs (no sample downloads).
packages/climate-ref/tests/unit/test_solve_helpers.py	Unit tests for catalog IO and solver result formatting using parquet-backed fixture.
packages/climate-ref/tests/unit/test_solve_regression.py	Regression tests that check solver output against deterministic baselines.
packages/climate-ref/tests/unit/test_solve_regression/test_solve_regression_per_provider_ilamb_.yml	Adds ILAMB regression baseline data for per-provider tracking.
changelog/529.feature.md	Changelog entry describing the new fixture + regression baseline approach.

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[Copilot]

Pull request overview

Copilot reviewed 48 out of 57 changed files in this pull request and generated 1 comment.

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[Copilot]

Pull request overview

Copilot reviewed 48 out of 57 changed files in this pull request and generated no new comments.

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[codecov]

Codecov Report

❌ Patch coverage is 98.90110% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...kages/climate-ref/src/climate_ref/solve_helpers.py	98.90%	0 Missing and 1 partial ⚠️

Files with missing lines	Coverage Δ
...kages/climate-ref/src/climate_ref/solve_helpers.py	98.90% <98.90%> (ø)

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[lewisjared]

@bouweandela We can now add regression tests for diagnostics executions and constraints

[bouweandela]

Awesome! 🥳