Part of epic #3602.

Scope

Add a user-facing setup guide for both Gonka access paths: GonkaGate (Phase 1) and native (Phase 2). Documentation must build with the project's mdBook setup and link from the existing provider docs.

Files to create / modify

• docs/src/llm-providers/gonka.md (new) — covers:
  • What gonka.ai is (one paragraph)
  • Path A: GonkaGate quickstart — sign up at https://gonkagate.com/en/register, create gp-... API key, zeph vault set ZEPH_COMPATIBLE_GONKAGATE_API_KEY gp-..., run zeph init and pick the Gonka option.
  • Path B: Native quickstart — install inferenced from https://github.com/gonka-ai/gonka/releases, inferenced keys add zeph, fund with GNK, run zeph init and pick the native Gonka option.
  • Pricing pointers (USD via gateway, GNK via native).
  • Troubleshooting: 401 on signature, clock skew, missing private key in vault.
• docs/src/SUMMARY.md — link the new page under the existing LLM providers section.

Acceptance

• mdbook build runs without warnings
• RUSTDOCFLAGS=\"--deny rustdoc::broken_intra_doc_links\" cargo doc --no-deps --workspace --features full clean
• Page renders correctly in the local mdbook server
• CHANGELOG.md [Unreleased] updated under ### Added

Depends on

None (parallelisable).

Size

M (~3h)