[codex] update site selection and report workflows - #45

Summary

• Updates site-selection workflow examples, documentation, config-reference artifacts, and report generation behavior.
• Finalizes the block HTML report workflow for catchment/site-selection reporting and removes legacy compatibility wrappers.
• Adds Windows path-length safeguards for data freeze restore, automatic exports, MF6 workspaces, and regression scratch paths.
• Aligns site-selection-to-testbed example filters with selected-site status handling.

Validation

• python -m pytest tests/unit/display/test_catchment_report_docs_contract.py tests/unit/test_pipeline_html_report_step.py tests/unit/site_selection/test_build_from_point_records.py tests/unit/site_selection/test_example_configs.py tests/unit/site_selection/test_legacy_contract.py tests/unit/simulation/test_flow_model_name_resolution.py tests/unit/simulation/test_results_post_run.py tests/regression/data/test_data_freeze_determinism.py -ra --tb=short -> 65 passed
• git diff --check HEAD~4..HEAD -> OK for the newly prepared commits

Notes

• Local uncommitted WIP files were intentionally left out of this PR, including examples/data/blobs/** and new Bretagne/testbed TOML drafts.