feat(tools): add GraphQL query and schema introspection tools

[mcao2]

Complex queries against NetBox currently require multiple sequential tool calls — fetching
a device, then its interfaces, then their IP addresses means 3+ round-trips, each
returning fully-expanded nested objects that consume significant context. NetBox's GraphQL
API (/graphql/) exposes the same data with precise field selection and cross-object
joins in a single request, but it's been inaccessible from the MCP server.

This adds three tools built around a new graphql() method on NetBoxRestClient:
netbox_graphql_query executes raw GraphQL queries, while netbox_graphql_schema_search
and netbox_graphql_type_details give LLMs a way to discover the schema before writing
queries — the same discovery-then-query pattern used by Cloudflare's GraphQL MCP server.

[abubnalitic-nbl]

Hey @mcao2, thanks for this PR, and genuinely sorry for how long it sat without a response.

We’ve just landed a CONTRIBUTING.md that states our scope more clearly - GraphQL and schema introspection are deliberately out of scope for this OSS server. The aim is to keep it simple, read-only over REST, and easy to fork. I appreciate that scope hadn’t been communicated before you started, and I’m sorry we didn’t give you a clear signal earlier.

So we won’t be merging this one. That said, the branch is a solid starting point if you want to run this capability against your own NetBox, forking under Apache 2.0 is first-class for exactly this kind of extension, and the code you’ve written is a clean basis. If you publish the fork, a discussion thread would be a welcome place to share it.

Thanks again for the patience and the care you put into this.