Extract resource presenter

[ewlarson]

Summary

• Add a ResourcePresenter and ResourceHydrationContext for resource JSON:API serialization and enrichments.
• Keep existing app.api.v1.utils entry points as compatibility wrappers around the presenter.
• Add contract-style tests for full/detail, search-result hydration, and homepage resource profiles.

Validation

• BTAA_SKIP_TEST_DB=1 venv/bin/python -m pytest tests/api/v1/test_resource_presenter.py tests/api/v1/test_utils.py (58 passed)
• venv/bin/ruff check app/api/v1/presenters app/api/v1/utils.py tests/api/v1/test_resource_presenter.py
• git diff --check

Notes

• A normal DB-backed focused run failed during local test DB setup because distribution_types.name=wmts already exists in the local test database.
• Endpoint compatibility tests with DB bootstrap skipped reached 37 passed / 3 skipped before tests using async_client attempted sandbox-blocked Postgres connections.