Remove misleading reference doc type alias renames

[danielporterda]

Summary

• Remove plain NewType = OldType aliases left from PR Tighten Python reference doc types #684 in the Python reference-doc typing surface.
• Inline generic JSON object/list types where a separate name was only a rename.
• Replace semantic aliases for Daml JSON modules, TypeDoc documents/exports, OpenRPC params/results, and protobuf metadata overlays with concrete TypedDict shapes.
• Add shared parsed-JSON and Mintlify navigation validators so JSON/YAML boundary code earns JsonValue, object, array, and nav item types instead of relying on cast(...).
• Add shape-specific loaders for Daml JSON modules, TypeDoc documents, AsyncAPI/OpenRPC documents, and protobuf metadata overlays.
• Keep only recursive structural aliases that are not simple renames: JsonValue, MintlifyNavItem, and MintlifyNavItems.

Validation

• direnv exec . python3 -m compileall -q scripts/generated_reference_nav.py scripts/reference_nav.py src/x2mdx/asyncapi/lifecycle.py src/x2mdx/asyncapi/models.py src/x2mdx/asyncapi/snapshots.py src/x2mdx/daml_json/models.py src/x2mdx/daml_json/snapshots.py src/x2mdx/jvm_docs/snapshots.py src/x2mdx/mintlify.py src/x2mdx/openrpc/lifecycle.py src/x2mdx/openrpc/models.py src/x2mdx/openrpc/snapshots.py src/x2mdx/protobuf/models.py src/x2mdx/protobuf/snapshots.py src/x2mdx/typedoc/models.py src/x2mdx/typedoc/snapshots.py src/x2mdx/types.py
• direnv exec . ruff check scripts/generated_reference_nav.py scripts/reference_nav.py src/x2mdx/asyncapi/lifecycle.py src/x2mdx/asyncapi/models.py src/x2mdx/asyncapi/snapshots.py src/x2mdx/daml_json/models.py src/x2mdx/daml_json/snapshots.py src/x2mdx/jvm_docs/snapshots.py src/x2mdx/mintlify.py src/x2mdx/openrpc/lifecycle.py src/x2mdx/openrpc/models.py src/x2mdx/openrpc/snapshots.py src/x2mdx/protobuf/models.py src/x2mdx/protobuf/snapshots.py src/x2mdx/typedoc/models.py src/x2mdx/typedoc/snapshots.py src/x2mdx/types.py
• direnv exec . mypy scripts/generated_reference_nav.py scripts/reference_nav.py src/x2mdx/asyncapi/lifecycle.py src/x2mdx/asyncapi/models.py src/x2mdx/asyncapi/snapshots.py src/x2mdx/daml_json/models.py src/x2mdx/daml_json/snapshots.py src/x2mdx/jvm_docs/snapshots.py src/x2mdx/mintlify.py src/x2mdx/openrpc/lifecycle.py src/x2mdx/openrpc/models.py src/x2mdx/openrpc/snapshots.py src/x2mdx/protobuf/models.py src/x2mdx/protobuf/snapshots.py src/x2mdx/typedoc/models.py src/x2mdx/typedoc/snapshots.py src/x2mdx/types.py
• Cast scan over src/x2mdx, scripts/generated_reference_nav.py, and scripts/reference_nav.py finds no cast(...) usage.
• Alias scan over the PR-touched files finds no plain rename aliases; only recursive structural aliases remain.
• PYTHONDONTWRITEBYTECODE=1 direnv exec . python3 -m pytest tests/test_api_reference_navigation.py tests/test_asyncapi.py tests/test_openrpc.py tests/test_daml_json.py tests/test_jvm_docs.py tests/test_protobuf.py tests/test_protobuf_nav.py tests/test_typedoc.py tests/test_typescript_bindings_reference.py -k 'not test_build_report_requires_status_for_non_deprecated_types and not test_build_report_tracks_lifecycle_from_local_jars and not test_cli_builds_pages_and_updates_docs_json and not test_cli_builds_overview_and_package_pages' passed: 31 passed, 4 deselected.
• git diff --check

Known base failures

The full focused pytest command currently has 4 failures that reproduce outside this branch:

• Three tests/test_jvm_docs.py cases fail while building fixture jars under Python 3.14 with struct.error: 'H' format requires 0 <= number <= 65535.
• tests/test_protobuf.py::ProtobufTests::test_cli_builds_overview_and_package_pages expects href="packages/com-example-v1", while the renderer emits href="./packages/com-example-v1".