Split Water Data adapters by collection family

[thodson-usgs]

Dependency

This PR is stacked on and must merge after #350. Its branch starts at #350 head 966bb618; while #350 remains open, this PR intentionally includes those commits in its comparison with main.

Summary

• split the Water Data implementation into time-series, metadata, measurements, reference, samples, and CQL collection-family modules
• retain dataretrieval.waterdata.api as a logic-free compatibility facade with unchanged public imports, signatures, function identity, metadata, warnings, exceptions, and deprecations
• separate OGC ambient context and schema/queryables execution from HTTP request construction
• declare explicit exports for active service and focused Water Data modules
• add public-contract snapshots and architecture fitness functions for facade purity, family isolation, adapter direction, and OGC boundaries
• document the adapter facade decision and intentional service-specific return contracts

Compatibility

The contract tests freeze all 19 Water Data facade exports and exact signatures. They also verify package/facade object identity, legacy __module__, Samples private compatibility names, and the facade get_ogc_data patch target.

Validation

• ruff check and ruff format
• strict mypy: 50 source files clean
• coverage run -m pytest tests/: 663 passed, 97% coverage
• make html: succeeded (4 pre-existing warnings)
• isolated wheel build/install: all six family modules, ogc.context, and ogc.schema importable outside the checkout; facade identity and module metadata preserved
• pre-commit: all hooks passed