Honor physicalName in Avro and JSON Schema exports

[henriquejsza]

Summary

• prefer ODCS physicalName with a name fallback for Avro schemas, records, fields, and enum names
• keep JSON Schema schema keys, properties, required, and pattern properties aligned with physical names
• add focused nested-schema regressions and a changelog entry

Validation

• uv run pytest -n0 tests/test_export_avro.py tests/test_export_jsonschema.py tests/test_roundtrip_jsonschema.py (18 passed)

• uv run pytest -n0 (2,110 passed, 14 skipped, 1 xfailed; Docker-dependent container files were not collected because no daemon was available)

• uv run ruff check

• uv run ruff format --check

• uv run python lint_examples.py (12/12)

• uv run pre-commit run --all-files

• uv build --wheel and CLI smoke exports for Avro and JSON Schema

• Tests pass (uv run pytest)

• Code formatted (uv run ruff check --fix && uv run ruff format)

• Docs updated (not required for this behavior fix)

• CHANGELOG.md entry added

Fixes #1494