Feature: GraphQL Schema Integration v1

## Focused Scope

Revisit GraphQL as a later optional schema integration after `interface-forge/json-schema` is stable.

## Proposed v1

- Add `interface-forge/graphql` as a separate optional entrypoint.
- Use `graphql` as an optional peer dependency.
- Accept SDL or `GraphQLSchema`.
- Generate factories for object and input object types.
- Support built-in scalars, enums, lists, non-null wrappers, simple nested objects, custom scalar generators, and max-depth handling.

## Out of Scope

- Apollo-specific mocks.
- Directives.
- Codegen plugins.
- Federation or schema stitching.
- File loading.
- Advanced union/interface handling.
- Static TypeScript inference from SDL.

The original scope combined too many products into one issue; this rewritten scope keeps the integration implementable and testable.