@spec coerce_value(term(), atom() | module() | tuple() | nil) :: term()

Coerces a decoded agtype scalar to its Ash attribute type.

Single source of truth for scalar coercion, shared by the vertex-read path (vertex_to_resource_attrs/3) and the traversal F3 source-key path (AshAge.ManualRelationships.Traverse). A nil/unknown type returns the value verbatim (identity), so callers may pass a type map that omits a field.

@spec vertex_to_resource_attrs(AshAge.Type.Vertex.t(), map(), map()) :: map()

Converts a vertex to a map of resource attributes.

• Extracts vertex.properties
• Includes vertex.id mapped to the resource's primary key
• Applies attribute_map for any name remapping
• Coerces types based on attribute_types (e.g., ISO8601 strings -> Date/DateTime)