Resolves custom remote typespecs for use ToolCall, types: [...].

A provider is asked for every remote type that is not built in (String.t/0, Keyword.t/0, Path.t/0 and the calendar types). It receives the remote module, the type name and the already-resolved argument types.

Return {:ok, %ToolCall.IR.Type{}} to describe the value, or :error to let the type fall back to {}. A returned node is validated recursively at compile time: unknown kinds, non-string or uncompilable patterns, malformed transforms, enum values, bounds, bound ordering, array minimums, formats, nullability, field metadata, and malformed fields/items/variants/additional raise an ArgumentError naming the provider and the remote type.

Implement coerce/1 to convert the wire-coerced value into the function's value domain; it runs after the built-in coercion. It is not called for an absent optional value, nor for nil accepted by the nullable shortcut. An explicit null for a non-nullable optional value is absent. If nil is accepted by any(), an enum containing nil, or a union with such a branch, it reaches coerce/1 like any other value. A raised, thrown or exited exception becomes {:error, {:invalid_transform, ...}} like any other coercion failure. It is a shorthand for a provider that resolves one type: a provider that handles several types can return %ToolCall.IR.Type{transform: {Module, :fun}} instead and leave coerce/1 undefined.